Python Workbook Olivieri

From

Flowchar ts to

P thon Activity Wor kbook L M.. O O SS Ph Olliivviieer  Liissaa M r ii,, S SJJ,, P hD D

From Flowcharts to Python

This Activity Workbook introduces students who already know flowchart fundamentals to the Python Programming language. The materials in this booklet were developed to help students collaborate with each other in the learning process and to become self-learners in an active learning environment. Students learn  programming concepts by doing programming and reflecting on t he results of the activities that t hey engage in.

Author: Lisa M. Olivieri, SSJ, Ph.D.

2

Name: _______________________________________ _______________________________________ Partners: ________________________________ ________________________________ Python Activity 1: Flowcharts and Python “What is the relationship between a flowchart and a Python program?”

Learning Objectives Students will be able to: Content: Explain how to display data in Python Explain how to create a comment in Python Determine the difference between a string a  string literal  literal  and  and a number  Process: Create print statements in Python Create Python Create Python code that displays results to calculated addition facts Discuss problems and programs with all group members Prior Knowledge Understanding of flowchart output symbols Further Reading Transitioning from Visual Logic to Python: Chapter Python:  Chapter 1 Critical Thinking Questions: Python Program

Flowchart

1. What does the line of Python code in the Python program do?  ____________________________  _________________________________________ _________________________ ________________________ _________________________ ________________  ___   ____________________________  _________________________________________ _________________________ ________________________ ___________________________ ________________ _ 2. Circle equivalent representation of the Python code in the flowchart. 3. Execute following code. What output is produced? a. print(“Hello, my name is Pat!”)   ________________________________  b. print(Hello, my name is Pat) c.

________________________________ ________________________________

print(“Hello.\nMy name is Pat”)  ________________________________

Python Activity 1: Flowcharts and Python 4.

Was there a problem with any of the sample code in question 3? If so, what caused the problem?  ___________________________  ________________________________________ __________________________ __________________________ _________________________ ____________  __________________________  ________________________________________ ___________________________ __________________________ _________________________ ____________

5.

What caused the different output format for samples “a” and “c” in question 3?  ___________________________  ________________________________________ __________________________ __________________________ _________________________ ____________  ___________________________  ________________________________________ __________________________ _________________________ ________________________ _____________ _

6.

What do you think the following Python statements output? a.

print(2+5)

_________________________

 b. print(2*5)

_________________________

c.

_________________________

print(“2+5”) 

d. print(“Age:”,20) 

_________________________

Enter the statements in the Python interpreter to verify your answers. 7.

Examine the output for each statement in question 6. a. What is the difference in the output for the statements in “a” and “c”  of question 6?  __________________________  ________________________________________ ___________________________ __________________________ _________________________ ____________  b. What caused the difference? ____________________________________________________  ___________________________  ________________________________________ __________________________ __________________________ _________________________ ____________ c. Which statements contain a string a  string literal  literal ?  ___________________________  ________________________________________ __________________________ __________________________ _________________________ ____________  ___________________________  ________________________________________ __________________________ __________________________ _________________________ ____________ d. What does the comma (,) do in the print statement in part “d”  of question 6? How does it affect the spacing of the output?  ___________________________  ________________________________________ __________________________ __________________________ _________________________ ____________  ___________________________  ________________________________________ __________________________ __________________________ _________________________ ____________

8.

Examine the following code and its output. What do the first three lines of the program do?

Output

 __________________________  ________________________________________ ___________________________ __________________________ _________________________ ____________  ___________________________  ________________________________________ __________________________ __________________________ _________________________ ____________ 4

Python Activity 1: Flowcharts and Python 9. What would happen if you placed a “#” in f ront of the code: in the  previous program?  ______________________________________________________________________________  ______________________________________________________________________________ Application Questions: Use the Python interpreter to design and check your work

1. Create a Python program containing three statements to implement the flowchart on the first page of this activity. Write the statements below.

2. Create one Python statement to produce the output expected from the flowchart. Be sure the output is printed on three lines.

3. Create a Python program containing two statements that prints the output to the right.  Have the program calculate the answers to the two arithmetic problems.

5

Python Activity 1: Flowcharts and Python

Notes and Questions  Make note of any questions you have about Activity 1 on this page.

6

Name: _______________________________________ Partners: ________________________________ Python Activity 2: Input and Variables in Python “How do you input and store data in a Python program?”

Learning Objectives Students will be able to: Content: Explain how to input data in Python Explain the meaning and purpose of a variable Determine if a variable name is valid Explain concatenation and the use of “+”  Process: Create input statements in Python Create Python code that prompts the user for data and stores it in a variable Create valid and good variable names Prior Knowledge Understanding of flowchart input symbols Further Reading Transitioning from Visual Logic to Python: Chapter 2

Critical Thinking Questions: Python Program

Flowchart Program

1. Enter and execute the Python program. What is printed on the screen when the Python program is executed?  _________________________________________________________________________________  _________________________________________________________________________________ input() and print() are functions   in Python.

2. Draw a line between each flowchart symbol and its corresponding Python code.

Python Activity 2: Input and Variables in Python 3. Examine the first line of Python program: name = input(“What is your name? ”) a. What happens when this line of code is executed?  ______________________________________________________________________________  b.

What appears on the screen when this line of code is executed?  ______________________________________________________________________________

The words that appear on the screen to tell the user what to enter are known as a prompt  .

c.

What happens to the data when the user enters their name and presses the Enter button? That is, where is their name stored?  ______________________________________________________________________________  –  The word name in the Python code is a variable  name given to a memory location used to store data.

4. What happens when you execute each of the following lines of Python code? a. name? = input(“What is your name?”)  ______________________________________________________________________________  ______________________________________________________________________________  b. your name = input(“What is your name?”)  ______________________________________________________________________________  ______________________________________________________________________________  c. 1st_name = input(“What is your name?”)  ______________________________________________________________________________  ______________________________________________________________________________  d. from = input(“Where were you born?”)  ______________________________________________________________________________  ______________________________________________________________________________  5. Examine the errors that occurred when executing the lines of code in question 5. Then examine the following lines of valid code. name2 = input(“What is your name?”) your_name = input(“What is your name?”) yourName = input(“What is your name?”)

List the rules that need to be followed to create a valid variable   name.  ________________________________________________________________________________  ________________________________________________________________________________   ________________________________________________________________________________  ________________________________________________________________________________  ________________________________________________________________________________  ________________________________________________________________________________ 8

Python Activity 2: Input and Variables in Python

6. Are the following variable names valid? Are they good names? Why or why not? Variable name  price costoffirstitem Ic firstName

7.

Comments about variable name

Execute the following lines of code. Is the output what you would expect? Why or why not?

 _________________________________________________________________________________   _________________________________________________________________________________ 8. Use the following set of Python statements to answer the questions below.

a. State the output for each of line of code.  _________________________________________________________________________________   _________________________________________________________________________________  _________________________________________________________________________________   _________________________________________________________________________________  _________________________________________________________________________________  b. Examine the first two print statements. How are they different? Does the difference affect the output?  _________________________________________________________________________________   _________________________________________________________________________________ c.

Notice that some statements include a comma (,) between the two literals being printed and some statements use a “+”. Do they produce the same output?  ____________________

d. Explain the purpose of the comma.  _________________________________________________________________________________  _________________________________________________________________________________ e. Why does the last print statement crash the program? What would you do to correct it?  _________________________________________________________________________________  _________________________________________________________________________________ “+” concatenates two strings. The strings can be string literals or a variable containing string literals. 9

Python Activity 2: Input and Variables in Python 9. State what is displayed on the screen when the following program is executed:

 _________________________________________________________________________________   _________________________________________________________________________________   _________________________________________________________________________________  _________________________________________________________________________________  Application Questions: Use the Python Interpreter to input your code and check your work

1. State a good variable name for an employee’s ID number.   ________________________________ 2. Write a line of Python code that prompts the user for the name of their favorite ice cream and stores it in a valid variable name. __________________________________________________________ 3. Crazy Sentence Program. Create a program that prompts the user for the name of an animal, a color, the name of a vehicle, and the name of a city. Then print a sentence that contains the user input in the following order. Include the additional words in the sample output as part of your output. Example: Assume the user enters the words: tiger, green, motorcycle, and Wildwood. The output would be:  green tiger drove the   motorcycle to   Wildwood. Th e   _________________________________________________________________________________   _________________________________________________________________________________   _________________________________________________________________________________  _________________________________________________________________________________  _________________________________________________________________________________   _________________________________________________________________________________   _________________________________________________________________________________  _________________________________________________________________________________

Notes and Questions  Make note of any questions you have about Activity 2 on this page.

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Python Activity 3 Part A: Arithmetic Operations and Assignment Statements

Name: _______________________________________ Partners: ________________________________ Python Activity 3 Part A: Arithmetic Operations and Assignment Statements “Get the program to compute that!” “How do I assignment values to variables?”

Learning Objectives Students will be able to: Content: Explain each Python arithmetic operator Explain the meaning and use of an assignment statement Review string literals and print statements Explain the use of “+” and “*” with strings and numbers Use the int()  and float() functions to convert string input to numbers for computation Incorporate numeric formatting into print statements Recognize the four main operations of a computer within a simple Python program  Process: Create input statements in Python Create Python code that performs mathematical and string operations Create Python code that uses assignment statements Create Python code that formats numeric output Prior Knowledge Understanding of Python print and input statements Understanding of mathematical operations Understanding of flowchart input symbols Further Reading Transitioning from Visual Logic to Python: Chapter 3

Critical Thinking Questions: Python Program

Flowchart Program

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Python Activity 3 Part A: Arithmetic Operations and Assignment Statements 1. Execute the print statements in the Python program. What is the output for each statement?  _________________________________________________________________________________  _________________________________________________________________________________  _________________________________________________________________________________  _________________________________________________________________________________  _________________________________________________________________________________  _________________________________________________________________________________  _________________________________________________________________________________  _________________________________________________________________________________ 2. Draw a line between each flowchart symbol and its corresponding line of Python code. 3. Explain the purpose of each arithmetic operation: a. + ________________________________________________________________________  b. -

________________________________________________________________________

c. *

________________________________________________________________________

d. **

________________________________________________________________________

e. /

_______________________________________________________________________

f.

//

_______________________________________________________________________

g. %

_______________________________________________________________________ An assignment statement is a line of code that uses a “=” sign. The statement stores the result of an operation performed on the right-hand side of the sign into the variable memory location on the lef0hand side.

4. Enter and execute the following two lines of Python code:

age = 15  print(“Your age is”, age)

a. What does the assignm ent statement : age = 15 do?  ______________________________________________________________________________  ______________________________________________________________________________  b.

5.

What happens if you replace the comma (,) in the print statement with a plus sign (+) and execute the code again? Why does this happen?  ______________________________________________________________________________  ______________________________________________________________________________ What is stored in memory after each assignment statement is executed? Assignment Statement answer = 6 ** 2 + 3 * 4 // 2 final = answer % 4

Computer Memory Answer Final

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Python Activity 3 Part A: Arithmetic Operations and Assignment Statements 6.

What happens if you try to use the “+” with strings instead of numbers? Test the following program:

The third line of code contains an assignment statement. What is stored in fullName when the line is executed?  ______________________________________________________________________________ a.

 b. How can you fix the output so that the words are separated?  ______________________________________________________________________________ The “+” concatenates   the two strings stored in the variables into one string. The assignment statement stored the results in the variable fullName. “+” can only be used when both operators are strings.

c.

What happens when you execute the following code? Why?

 ______________________________________________________________________________  ______________________________________________________________________________ 7.

Before entering the following code into the Python interpreter, try to figure out what you think the statement should print.

 Now execute it. What does it do? Is this what you thought it would do?  ______________________________________________________________________________  ______________________________________________________________________________ 8.

Let’s take a look at a program that prompts the user for two numbers and subtracts them. Execute the following code.

a.

What output do you expect?

_____________________________________________

 b.

What is the actual output?

_____________________________________________

c.

Revise the program in the following manner: Between lines 2 and 3 add the following lines of code:

num1 = int(firstNumber) num2 = int(secondNumber)

13

Python Activity 3 Part A: Arithmetic Operations and Assignment Statements

 Next, replace the statement:

difference = firstNumber – secondNumber with the statement:

difference = num1 – num2 Execute the program again. What output did you get? ________________________ d.

Explain the purpose of the function int().  ______________________________________________________________________________  ______________________________________________________________________________

e.

Explain how the changes in the program produced the desired output.  ______________________________________________________________________________  ______________________________________________________________________________

Application Questions: Use the Python Interpreter to check your work

1.

Write the line of Python code that calculates and prints the answer to the following arithmetic expressions: a. 8 to the 4 th power ___________________________________________________  b.

The sum of 5 and 6 multiplied by the quotient of 34 and 7 using floating point arithmetic  _______________________________________________________________________

2.

3.

Write an assignment statement that stores the remainder obtained from dividing 87 and 8 in the variable leftover   ______________________________________________________________________________ Assume:

courseLabel = “CMSC” courseNumber = “190”

Write a line of Python code that concatenates the label with the number and stores the result in the variable courseName. Be sure that there is a space between the course label and the course number when they are concatenated.

 _________________________________________________________________ 4.

Create a program the outputs the total cost of a lunch order. Users should be prompted to input the number of hamburgers, fries, and drinks they want and the program should print the total cost of the order. The hamburgers cost 2.00, fries cost 1.50, and drinks cost 1.00. Be creative and  professional in prompting the user for the information and in displaying the output.  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________ 

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Name: _______________________________________ Partners: ________________________________ Python Activity 3 Part B: Arithmetic Operations and Assignment Statements “Get the program to compute that!”

Learning Objectives Students will be able to: Content: Incorporate numeric formatting into print statements Recognize the four main operations of a computer within a simple Python program  Process: Create Python code that uses assignment statements Create Python code that formats numeric output Prior Knowledge Understanding of Python print and input statements Understanding of mathematical operations Understanding of flowchart input symbols Further Reading Transitioning from Visual Logic to Python: Chapter 3

Critical Thinking Questions:

1. So far you have not been concerned about formatting output on the screen. Now you will discover how Python allows a programmer to precisely format output. Some of the differences are very subtle, so take notice of the differences in outputs. Start by entering and executing the following code.

a.

What is the problem with the manner in which the output is displayed?  _____________________________________________________________________________  ______________________________________________________________________________

 b. Replace the last line of code with the following:

 print("Total cost of laptops: %.2f" % price) Discuss the change in the output.  _____________________________________________________________________________  ______________________________________________________________________________ c.

Replace the last line of code with the following:

 print("Total cost of laptops: $%.2f" % price) Discuss the change in the output.  ______________________________________________________________________________  ______________________________________________________________________________

Python Activity 3 Part B: Arithmetic Operations and Assignment Statements d. Experiment with the number “.2” in the print statement by substituting the following numbers and explain the results. .4 ________________________________________________________________________ .0

________________________________________________________________________

.1

________________________________________________________________________

.8

________________________________________________________________________

e. Now try the following numbers in the same print statement. These numbers contain a whole number and a decimal. Explain the output for each number. 2.5 _______________________________________________________________________ 8.2 _______________________________________________________________________ 3.1 _______________________________________________________________________ f.

Explain what the formatting code: “%n.nf % variable”  does in a print statement where n.n represents a number.  _____________________________________________________________________________  ______________________________________________________________________________

g. Revise the print statement by changing the “ f” to “d” and the decimal number to a whole number. Explain the sample formatting statements:

 print("Total cost of laptops: %2d" % price)  print("Total cost of laptops: %10d" % price)  ______________________________________________________________________________  ______________________________________________________________________________ h. Explain how “%nd % variable”  formats numeric data. “n” represents a whole number.  ______________________________________________________________________________  ______________________________________________________________________________ Computers perform four main operations on data: Input data into a computer Output data to a screen or file Process data using arithmetic, logical, searching or sorting operations Store data

2.

Use the following program to answer the questions below.

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Python Activity 3 Part B: Arithmetic Operations and Assignment Statements a.

Using the code and comments in the program listed above, explain how the four main operations are implemented in the program.  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________

 b.

There is one new concept exemplified in this sample program. What is it? From the corresponding output, determine what it does.  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________

 

Application Questions: Use the Python Interpreter to check your work 1. Write one line of Python code that will print the word “Happy!” one hundred times.  ______________________________________________________________________________

2.

3.

Assume:

itemCost = input(“Enter cost of item: “)

a.

Write one line of code that calculates the cost of 15 items and stores the result in the variable totalCost  ________________________________________________________________________

 b.

Write one line of code that prints the total cost with a label, a dollar sign, and exactly two decimal places. Sample output: Total cost: $22.50  ________________________________________________________________________

Assume:

height1 = 67850 height2 = 456 Use Python formatting to write two print statements that will produce the following output exactly at it appears below:

 ______________________________________________________________________________  ______________________________________________________________________________ 4. You have already completed the following program in a previous activity. Format the output. Create a program the outputs the total cost of a lunch order. Users should be prompted to input the number of hamburgers, fries, and drinks they want and the program should print the total cost of the order. The price of hamburgers is 2.00, fries is 1.50, and drinks is 1.00. Be creative and professional in prompting the user for the information and in displaying the output.  _____________________________________________________________________________________  _____________________________________________________________________________________  _____________________________________________________________________________________  _____________________________________________________________________________________  _____________________________________________________________________________________  _____________________________________________________________________________________  _____________________________________________________________________________________  _____________________________________________________________________________________  _____________________________________________________________________________________

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Python Activity 3 Part B: Arithmetic Operations and Assignment Statements Notes and Questions  Make note of any questions you have about Activity 3 on this page.

18

Name: _______________________________________ Partners: ________________________________ Python Activity 4: Predefined Functions “How can I use the built -in code that is already part of Python?”

Learning Objectives Students will be able to: Content: Explain the purpose of a predefined function Explain the functions: abs(), pow(), int() round(), random Explain the math library functions: floor() and ceil() Explain the use of the import statement Explain the purpose of a function argument  Process: Write code that uses predefined functions Prior Knowledge Python concepts from Activities 1-3 Understanding of flowchart input symbols Further Reading Transitioning from Visual Logic to Python: Chapter 4 Model 1: Predefined functions in Python print(), round(), abs(), pow(), int(), etc. are known as predefi ned f uncti ons  . Information that a function needs to do its work is sent to the function between the parentheses (). This information is known as an  function argument. To use a function, call the function. input(“Enter your name”) is a call to the input  sending the string “Enter your name” as an argument Critical Thinking Questions: 10. Circle the predefined functions in the following program.

11. Draw a line between each statement in the Python program and its corresponding statement in the flowchart.

Python Activity 4: Predefined Functions 12. Enter and execute the Python program on the previous page. a. What is the output for each statement ? print(abs(-4.67)) _________________________ print(pow(5,3)) _________________________ print(pow(49,.5)) _________________________ print(int(34.8)) _________________________ print(round(6.9)) _________________________ import random print(random.randint(1,100)) ___________________  b. What is the difference between the round() function and the int() function?  ______________________________________________________________________________  ______________________________________________________________________________ 4. What is the output for each line of code? Verify your answers by executing the code and explain the answer given by the interpreter. a. abs(4.5) _________________________________________________  b. int(“678”) 

_________________________________________________

c. round(-5.6)

_________________________________________________

d. import random random.randint(4,10) ___________________________________________ What is the purpose of “ import random”? What happens if you omit that line of code?  ______________________________________________________________________________  ______________________________________________________________________________ 5.

Write a definition of a predef in ed fu nction .  ______________________________________________________________________________  ______________________________________________________________________________

6.

Circle the argument in the following predefined function: number = 45.78 answer = round(number)

7.

How many arguments can a function have?

8.

answer = pow(4,3) . What is/are the argument(s) in this code? ______________________

9.

If a function contains more than one argument, do you think the order of the arguments makes a difference? Explain your answer.  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________

_______________________________________

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Python Activity 4: Predefined Functions 10.

Execute the following code: import math x = 4.7 y = 5.3 z = -4.8 a = -3.2 print(math.ceil(x)) print(math.ceil(y)) print(math.ceil(z)) print(math.ceil(a)) print(math.floor(x)) print(math.floor(y)) print(math.floor(z)) print(math.floor(a)) a.

Explain what the ceil() function does.  ________________________________________________________________________  ________________________________________________________________________

 b.

Explain the purpose of the floor() function.  ________________________________________________________________________  ________________________________________________________________________

c.

Why are the calls to the math() and ceil() functions preceded by “ math.”?  ________________________________________________________________________  ________________________________________________________________________

Application Questions: Use the Python Interpreter to check your work

1.

Write a line of code that prints the integer portion of the number 21.45.  ______________________________________________________________________________

2.

Write code that prompts the user for a floating point number and prints the smallest integer that is larger than the number the user entered.  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________

3.

Write a line of code that prints a random number between one and 6.  ______________________________________________________________________________  ______________________________________________________________________________

4.

Assume that a user enters any number and that the number is stored in the variable userNumber. Write a line of code that converts the input to a float. Then write a line of code that prints the  positive value of the user’s input.  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________

5.

Write a line of code that calculates the square root of 900 and stores the result in the variable answer.  ______________________________________________________________________________ 21

Python Activity 4: Predefined Functions

Notes and Questions  Make note of any questions you have about Activity 4 on this page

22

Name: _______________________________________ Partners: ________________________________ Python Activity 5: Boolean Expressions and Selection Statements “True or False and making choices”

Learning Objectives Students will be able to: Content: Explain the three types of programming structures Explain how conditional operators and logical operators are used in programming Use conditional operators with strings and numeric values Implement the Python syntax of an if/else statement Determine good test data for programs that include if/else statements  Process: Write code that includes if statements and if/else statements Write correct Boolean expressions and compound expressions Prior Knowledge Python concepts from Activities 1-4 Understanding of flowchart input symbols Further Reading Transitioning from Visual Logic to Python: Chapter 5 Model 1: Programming Structures Sequence Structure

Decision or Branching Structure

Looping Structure

Critical Thinking Questions: 1. Each of the flowchart symbols in the chart above represents lines or segments of code. After examining the chart, write a description of: a. sequence structure ________________________________________________________  ________________________________________________________________________

 b.

decision or branching structure _____________________________________________  _______________________________________________________________________

c.

looping structure ____________________________________________________  ________________________________________________________________________

Python Activity 5: Boolean Expressions and Selection Statements 2.

Which structure best describes the types of Python programs you have written so far? Do you think this structure is the best structure to use for all programs? Why or why not?  ______________________________________________________________________________  ______________________________________________________________________________

3.

Which structure allows the programmer to create code that decides what code is executed?  _____________________________________________________________________________ Model 2: Conditional Operators Conditional operators, also known as relational operators, are used to compare the relationship  between two operands. Expressions that can only result in one of two answers are known as Boolean expression.

4.

Determine the meaning of each of the following conditional operators. If you are not sure of the meaning of any symbol, create some example expressions, type them into the Python interpreter  (see figure to the right) and examine the results. a.

<

___________

b.

>

____________

c.

<=

___________

d.

>=

____________

e.

!=

___________

f.

==

____________

5. What is the result of each of the following expressions? Assume x = 4, y = 5, z = 4 a.

x>y

______________________________________

 b.

x
______________________________________

c.

x == y

______________________________________

d.

x != y

______________________________________

e.

x >= z

______________________________________

f.

x <= z

______________________________________

g.

x+y>2*x

______________________________________

h.

y * x – z != 4 % 4 + 16

______________________________________

i.

pow(x,2) == abs(-16)

______________________________________

6. What is the result of the following expressions? Assume word1 = “hello”, word2 = “good-bye” a.

word1 == word2

______________________________________

 b.

word1 != word2

______________________________________

c.

word1 < word2

______________________________________

d.

word1 >= word2

______________________________________

24

Python Activity 5: Boolean Expressions and Selection Statements 7. Explain how the the conditional conditional operators are are used when the the operands are are strings.  ____________________________  _________________________________________ _________________________ ________________________ _________________________ _____________  ____________________________  _________________________________________ _________________________ ________________________ _________________________ _____________ 8. There are only two possible answers to the expressions in questions 5 and 6. What are they?  __________________________  _______________________________________ __________________________ __________________________ ________________________ ______________ ___ Model 3: IF/ELSE Statement Flow chart

Python Program

9.

What is the Python code equivalent of the diamond flowchart symbol in the program above?  ________________________  _____________________________________ __________________________ __________________________ ______________________ _________

10.

Enter and execute the following code. Use various values for the original cost cost and the sale price.

Explain what the following lines of code do. Each line appears in the program above. originalPrice = int(originalPric int(originalPriceString) eString) a.  ____________________________  _________________________________________ _________________________ _________________________ ___________________ ______  b. percentOff =(originalPrice - salePrice)/originalPrice * 100  ____________________________  _________________________________________ _________________________ ________________________ ___________________ _______ c. print("Sale price: $%.2f" %salePrice)  ____________________________  _________________________________________ _________________________ _________________________ ___________________ ______ d. print("Percent off: %2d" % percentOff + "%")  ____________________________  _________________________________________ _________________________ ________________________ ___________________ _______ e. if percentOff >= 50: print("You got a great sale!")  ____________________________  _________________________________________ _________________________ _________________________ ___________________ ______

25

Python Activity 5: Boolean Expressions and Selection Statements 11.

Revise the program in #10. If the percent off is 50% or more print “Congratulations!” in addition to what is already printed. Use a second print statement to do this. Write the code for this part of the program.  __________________________  ________________________________________ ___________________________ __________________________ _________________________ ____________  ___________________________  ________________________________________ __________________________ __________________________ _________________________ ____________  ___________________________  ________________________________________ __________________________ __________________________ _________________________ ____________  ___________________________  ________________________________________ __________________________ _________________________ ________________________ _____________ _

12.

Revise the program in #12 so that it prints “Done!” when the program is complete –  no –  no matter what the percent off is. How does the placement of this line of code differ from the placement of the code created for #12?  ___________________________  ________________________________________ __________________________ __________________________ _________________________ ____________  ___________________________  ________________________________________ __________________________ __________________________ _________________________ ____________

Python Program

Flowchart

13.

Compare the flowchart above with the corresponding correspondi ng Python Program. Carefully compare if/else statement in the two programs. Enter and execute the Python program above. a.

Test the program at least three times. List the three test data you used and the corresponding correspondi ng output. Explain why they were the best data to use as a test for the  program.  ___________________  ___________________ __________________ __________________ ___________________ ___________________  ________________________  _____________________________________ __________________________ __________________________ ______________________ _________  ________________________  _____________________________________ __________________________ ____________________________ ______________________ _______  ________________________  _____________________________________ __________________________ __________________________ ______________________ _________

26

Python Activity 5: Boolean Expressions and Selection Statements  b.

Now you want want to add another another print print statement statement to the Python program program above above so that it  printed “That’s “That’s really really hot!” when when the water water is 212 degrees or or hotter. Rewrit Rewritee the code  below with this statement statement included. included.  ____________________________  _________________________________________ _________________________ ________________________ ___________________ _______  ____________________________  _________________________________________ _________________________ ________________________ ___________________ _______  ____________________________  _________________________________________ _________________________ _________________________ ___________________ ______  ____________________________  _________________________________________ _________________________ ________________________ ___________________ _______  ____________________________  _________________________________________ _________________________ ________________________ ___________________ _______  ____________________________  _________________________________________ _________________________ ________________________ ___________________ _______ We can use logical operators to determine logic between conditions (relational expressions).

14.

Sometimes you want to test more than one condition to determine which code segment should be executed. You can use the following logical operators to create compound conditions. Examine each operator and a sample of its use. Provide an explanation of how each operator works. Operator

15.

Example

Explanation

and

(age >= 17) and (hasLicense = = true)

or

(cost < 20.00) or (shipping = = 0.00)

not

not (credits> 120)

Assume the value of the variable numBooks is 40. State the values of each each of the Boolean expression. Expression

Value

(numBooks > 5) and (numBooks < 100) (numBooks < 5) or (numBooks > 100) not(numBooks * 10 == 100)

16.

Suppose you want to determine if a student is ready ready to graduate. The 3 criteria for graduation graduation are that the student has earned at least 120 credits, their major GPA is at least 2.0 and their general GPA is also at least 2.0.

Missing Boolean expression

27

Python Activity 5: Boolean Expressions and Selection Statements Which Boolean expression expression would be the correct test for Python code? a. numCredits >= 120 or majorGPA >= 2.0 or overallGPA >= 2.0  b. numCredits > 120 and majorGPA majorGPA > 2.0 or overallGPA overallGPA > 2.0 c. numCredits > 119 and majorGPA >= 2.0 and overallGPA overallGPA >= 2.0 d. numCredits >= 120 and majorGPA >= 2.0 and overallGPA >= 2.0 17.

Enter and execute the program in #16. Include your choice for the correct Boolean expression. Create several data sets to test all possibilities for the Boolean expression. List the data you used to test all possibilities possibilities for the expression. Data Set

numCredits

majorGPA

overallGPA

Expression Result (True or False)

1 2 3 4 5 6 7 8 9 10

Application Questions: Use the Python Interpreter to check your work

1.

Write a Boolean expression that tests if the value stored in the variable num1 is equal to the value stored in the variable num2.  ___________________________  ________________________________________ __________________________ __________________________ _________________________ ____________

2.

Write a Boolean expression that tests if the value stored in the variable time is less than the value stored in the variable maxTime or if the value stored in the variable cost is less than the value stored in the variable maxCost  ___________________________  ________________________________________ __________________________ __________________________ _________________________ ____________

3.

Write the code for an if statement that adds 5 to the variable num1 if the value stored in the variable testA equals 25. Otherwise subtract 5 from num1.  ___________________________  ________________________________________ __________________________ __________________________ _________________________ ____________

4.

Write the code for an if statement that prints a random number between one and 6 if the value stored in the variable isValid equals the Boolean value true.  ___________________________  ________________________________________ __________________________ __________________________ _________________________ ____________  ___________________________  ________________________________________ __________________________ _________________________ ________________________ _____________  _   ___________________________  ________________________________________ __________________________ __________________________ _________________________ ____________

28

Python Activity 5: Boolean Expressions and Selection Statements 5.

Write a Python program that prompts the user for the cost of two items to be purchased. Then  prompt the user for their payment. If they enter an amount that is less than the total cost of the two items, print a message that tells them how much they still owe. Otherwise, print a message that thanks them for their payment and tells them how much change they will receive. Thoroughly test your code for all possible input.  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________

6.

Write a Python program that prompts the user for a word. If the word comes between the words apple and pear alphabetically, print a message that tells the user that the word is valid, otherwise, tell the user the word is out or r ange.  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________

7.

Write a Python program that prompts the user for a multiple of 5 between 1 and 100. Print a message telling the user whether the number they entered is valid.  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________

29

Python Activity 5: Boolean Expressions and Selection Statements Notes and Questions  Make note of any questions you have about Activity 5 on this page.

30

Name: _______________________________________ Partners: Python Activity 6: Functions

________________________________

“Modularizing your code”

Learning Objectives Students will be able to: Content: Explain the meaning and purpose of a function Recognize a function definition, function header, and function call in a program Combine the use of functions with if/else statements Explain programs that use the same function multiple times Use good test data for programs that include functions  Process: Write code that includes function definitions and function calls Write programs that incorporate functions and if/else statements Prior Knowledge Python concepts from Activities 1-5 Understanding of flowchart input symbols Further Reading Transitioning from Visual Logic to Python: Chapter 6 Critical Thinking Questions:

Python Program

Flowchart

Python Activity 6: Functions A function is a segment of code that performs a single task.

1.

Closely examine the flowchart and Python program above. a. Draw arrows between each flowchart symbol and the equivalent Python code. A function definition is the segment of code that tells the program what to do when the function is executed. The first line of a function definition is known as the function header

2.

 b.

What Python keyword is used to indicate that a code segment is a function definition?  ________________________________________________________________________

c.

What is the function header in the Python code above?  ________________________________________________________________________

d.

The name of the function is in the function header. What is the name of the function?  ________________________________________________________________________

e.

Examine the Python function. Explain the syntax required for a function: indentation, etc.  ________________________________________________________________________  ________________________________________________________________________

f.

Enter and execute the Python program. What is the output?  ________________________________________________________________________

g.

What line of code would you add to the program to print the last two lines twice? Where would you add the code?  ________________________________________________________________________  ________________________________________________________________________

Examine the following program

a.

Label the function definition and the function call.

 b.

The function call and the function definition each include a variable within the  parentheses. The variable in this role is known as an argument. What is the argument in the function definition? What is its purpose?  ________________________________________________________________________  ________________________________________________________________________ 32

Python Activity 6: Functions

c.

In this example the argument in the function definition and the argument in the function call have the same name. Is this required? _______________________________

d.

Enter and execute the program. Verify your answer to question ‘c’ by changing the variable name in the main program from radius to number. Do not change the variable name in the function definition. Does the program still work? __________________

e.

Write a line of code that calls the calculateArea function and sends the value “6” as the argument. Add the line of code to the main program and execute it to be sure it works  properly. _______________________________________________________________

f.

Add a second function to the program that calculates and prints the diameter of a circle, given the radius as an argument (parameter). Place the function definition above the main  part of the program. Write the function below.  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________

g.

Add another line of code to the main part of the program that calls the function that was created in part ‘f’. Send the radius entered by the user as the argument to the function.  ________________________________________________________________________

3.

What is the purpose of a function? Why do programmers use them?  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________ 

4.

Carefully examine the following program.

a.

What is the first line of code executed by the Python interpreter?  ________________________________________________________________________ 33

Python Activity 6: Functions

 b.

Enter and execute the program. Use the following test data and indicate what the output is for each set of data. Data Set 1 2 3 4

Operand 1 2 3 34 4

Operand 2 6 8 23 5

Operator + + /

Result

c.

What problems did you notice when you entered Data Sets 3 and 4?  ________________________________________________________________________  ________________________________________________________________________   ________________________________________________________________________ 

d.

Add code to the program that would warn the user about the problems that could occur when data similar to that in Data Sets 3 and 4 are entered. See sample output below. List the lines of code below the sample output.

 ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________

34

Python Activity 6: Functions So far, the functions you have printed any results within the function. They did not send  back any information to the original calling code. Functions t hat do not send back information to where they are called are known as void functions. Functions often send  back or return the result and are known as value returning functions.

5.

6.

Enter and execute the code below. Carefully examine the code.

a.

What is the new keyword used in the function definition? What do you think the keyword tells the program to do?  ________________________________________________________________________  ________________________________________________________________________

 b.

Write the line of code from the program that includes the function call to getSmaller .  ________________________________________________________________________

c.

In a void function, the function call is on a line by itself. Why is this function call  placed on the right-hand-side of an assignment statement?  ________________________________________________________________________  ________________________________________________________________________

d.

What are the arguments used for the function call? _______________________________

Examine the following Python program.

a.

What does the program do?  ________________________________________________________________________

 b.

Circle the function call. What is different about the placement of the function call?  ________________________________________________________________________ 35

Python Activity 6: Functions

7.

c.

Is the function a void function or a value returning function? ____________________

d.

Why is the import statement needed in this program?  _______________________________________________________________________

The following Python program performs the same operations and produces the same output as the  previous program. Describe the major differences between the two programs. Edit the previous  program so that it looks like this one and execute it.

 ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________ Application Questions: Use the Python Interpreter to check your work 1. Write a function that draws a frog. Call the function to be sure it works. Sample frog:

 ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________

36

Python Activity 6: Functions 2.

Expand the program in #1 to produce the following output.  ____________________________________________________________  ____________________________________________________________  ____________________________________________________________  ____________________________________________________________  ____________________________________________________________  ____________________________________________________________  ____________________________________________________________  ____________________________________________________________  ____________________________________________________________  ____________________________________________________________  ____________________________________________________________  ____________________________________________________________

3.

Write a Python program that prompts the user for three words and prints the word that comes last alphabetically. Use a function to create the program.  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________

37

Python Activity 6: Functions Notes and Questions  Make note of any questions you have about Activity 6 on this page.

38

Name: _______________________________________ Partners: ________________________________ Python Activity 7: Nested IF/ELSE Statements “Decisions, decisions – decisions within decisions!”

Learning Objectives Students will be able to: Content: Explain the purpose of a nested if-else statement Explain how to use Python if-elif structure Explain how to test code using Python if-elif structure  Process: Write code that includes if-elif statements Write code that uses if-elif statements and functions Prior Knowledge Python concepts from Activities 1-6 Understanding of flowchart input symbols Further Reading Transitioning from Visual Logic to Python: Chapter 7 Critical Thinking Questions:

1.

Closely examine the flowchart and Python program above.

Python Program

Flowchart

Python Activity 7: Nested IF/ELSE Statements a.

Draw arrows between each flowchart symbol and the equivalent Python code.

 b. In the Python code, circle the if/else statement that is nested within another if/else statement. c.

Enter and test the code. List five numbers that you would use to test this program. Indicate why you chose the numbers.  Number

2.

Why chosen

Enter and execute the following Python program using the same data as you used for #1c.

a.

How does the output for this program compare with the output for the previous program?  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________

 b. What new keyword is used in this program? _______________________________________ c.  Notice the syntax of this program compared to the previous program. Which program contains simpler indentation? _____________________________________________ elif is the Python keyword that represents else if  and allows you to test for one of several options . As soon as one of the tests is true, the rest are ignored.

d. You can use elif as many times as you need to. Suppose you wanted to add the comment “Good!” for grades that are between 80 and 89. Where would you add it? Write the code for this additional choice.  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________ e.

Does the placement of an additional elif clause matter? ______________________________

f.

When is the code associated with the else statement executed?  ___________________________________________________________________________ 40

Python Activity 7: Nested IF/ELSE Statements

g. Describe how an if/elif/else statement works.  ___________________________________________________________________________   ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________ h.

Change the program in #2 so that it prints the following messages. Write the code below. Greater than 90 Between 80 and 89 Between 70 and 79 Between 60 and 69” Less than 60

“Very Good!” “Good!” “Satisfactory” “Fair” “Poor”

 ___________________________________________________________________________   ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________   ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________   ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________ i.

3.

Make a final change to the program so that it prints an error message if the grade entered is greater than 100 or less than 0.  ___________________________________________________________________________   ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________

Is the use of the else statement mandatory when creating an if/elif statement? Explain your answer.  ___________________________________________________________________________   ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________

41

Python Activity 7: Nested IF/ELSE Statements Application Questions: Use the Python Interpreter to check your work 1. Write an if/elif statement that assigns a value to the variable bonus depending on the amount of sales. Assume the amount of the sales is stored in a variable called sales. Sales >= 100,000 >= 75,000 >= 50,000 >= 25,000

Bonus 10,000 5,000 2,500 1,000

 _________________________________________________________________________________  _________________________________________________________________________________   _________________________________________________________________________________  _________________________________________________________________________________  _________________________________________________________________________________   _________________________________________________________________________________  _________________________________________________________________________________  _________________________________________________________________________________   _________________________________________________________________________________  _________________________________________________________________________________  _________________________________________________________________________________   _________________________________________________________________________________ 2. Carefully examine and then complete the following Python program. The program prompts the user to enter a number between 1 and 5 and also generates a random number between 1 and 5. The  program prints the number the user enters and prints the random number. The program then compares the two numbers. If the numbers are the same, it prints the message “You picked the same number as the computer!”. If the number the user entered is higher than the random number, the  program should print “Your number is higher than the computer’s number.” Otherwise, it should  print: “Your number is smaller than the computer’s number”. Explain what the if/else statement does in the Main Program.

42

Python Activity 7: Nested IF/ELSE Statements

.

43

Python Activity 7: Nested IF/ELSE Statements Notes and Questions  Make note of any questions you have about Activity 7 on this page.

44

Name: _______________________________________ Partners: ________________________________ Python Activity 8: Looping Structures – WHILE Loops “Repeating code”

Learning Objectives Students will be able to: Content: Explain the three parts of a loop Explain the syntax of a while loop Explain sentinel-controlled and counter controlled loops Explain short-cut operators  Process: Write code that includes  sentinel-controlled and counter controlled loops Write code that uses short-cut operators Prior Knowledge Python concepts from Activities 1-7 Understanding of flowchart input symbols Further Reading Transitioning from Visual Logic to Python: Chapter 8 Critical Thinking Questions 1. Closely examine the flowchart and Python program below. A looping structure allows a block of code to be repeated one or more times. A while loop is one of the two looping structures available in Python.

Python Program

Flowchart

a. Draw arrows between each flowchart symbol and the equivalent Python code.  b. In the Python code, circle all the code associated with the WHILE loop.

Python Activity 8: Looping Structures – WHILE Loops c.

Enter and test the code. What does the line of code: x=x+1 do?  ___________________________________________________________________________

d. How does the Python interpreter know what lines of code belong to the loop body?  ___________________________________________________________________________ e.

Every loop structure requires three actions. Identify the line of code in the Python  program that corresponds to each of the three actions.  Initialize a variable used in the test condition:  ________________________________________________________________________  Include a test condition that causes the loop to end when the condition is false:  ________________________________________________________________________ Within the loop body, update the variable used in the test condition:  ________________________________________________________________________ 





2.

Enter and execute the following code.

 _______________________________   __________________________________________________  __________________________________________________  __________________________________________________  __________________________________________________  __________________________________________________  __________________________________________________  __________________________________________________

3.

a.

Beside each line of code below explain what the code does.

 b.

Explain the difference between the two print statements.  ________________________________________________________________________  ________________________________________________________________________

The following code should print the numbers from 1 to 10, but it does not print anything. Correct the problem.

number = 12  while number <= 10:  print(number) number = number + 1 4.

Enter and execute the following code:

number = 0  while number <= 10:  print(number) number = number - 1 a.

Describe the output.

____________________________________________________ 46

Python Activity 8: Looping Structures – WHILE Loops

6.

 b.

What caused the output to be what it was?  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________

c.

Does the program end? Why or why not? ________________________________  _______________________________________________________________________

Enter and execute the following code:

number = 1  while number <= 10: if number % 2 == 0:  print(number, end= " number = number + 1

7.

")

a.

State the output.  ________________________________________________________________________

 b.

What caused the output to display on one line?  ________________________________________________________________________  ________________________________________________________________________

c.

What control structures are used in this code?  ________________________________________________________________________

We want to create a program that prompts the user to enter a number between 1 and 10. As long as the number is out of range the program re-prompts the user for a valid number. Complete the following steps to write this code. a.

Write a line of code the prompts the user for number between 1 and 10.  ________________________________________________________________________

 b.

Write a Boolean expression that tests the number the user entered by the code in step “a.” to determine if it is not in range.  ________________________________________________________________________

c.

Use the Boolean expression created in step “b.” to write a while loop that executes when the user input is out of range. The body of the loop should tell the user that they entered an invalid number and prompt them for a valid number again.  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________

d.

Write a line of code that prints a message telling the user that they entered a valid number.  ________________________________________________________________________

e.

Put the segments of code from steps “a-d” together. Enter and execute the code. Does it work properly? If not, correct it and test it again. _________________________

47

Python Activity 8: Looping Structures – WHILE Loops f.

How many times does the loop execute? ______________________________________ A looping structure for which you know the number of times it will execute is known as a count-controlled loop.

8.

Sometimes a programmer does not know how many times data is to be entered. For example, suppose you want to create a program that adds an unspecified amount of positive numbers entered by the user. The program stops adding numbers when the user enters a zero or a negative number. Then the program prints the total. Before creating this program, review the three actions required for all loops: a.

 Initialize a variable that will be used in the test condition: What will be tested to determine if the loop is executed or not? Write a line of code that initializes a variable to  be used in the test condition of the loop for this program. The variable should contain a value entered by the user.  ________________________________________________________________________

 b.

 Include a test condition that causes the loop to end when the condition is false: What is the test condition for the while loop used in this program?  ________________________________________________________________________

c.

Within the loop body, update the variable used in the test condition:  Write the code for the loop body. Include the code to update the variable in the test condition.  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________

d.

Is this a count-controlled loop? Why or why not?  ________________________________________________________________________

e.

Complete the program. Enter and execute the code. Does it work properly? __________ Short-cut operators  provide a concise way of creating assignment statements when the variable on the left-hand side of the assignment statement is also on the right-hand side. The addition short-cut operator (+=) is usually used for incrementing a variable.

9.

Enter and execute the following code:

number = 1 number += 3  print(number) a.

What does the “+=” shortcut operator do?  ________________________________________________________________________

 b.

The code: x += 5 is equivalent to which of the following lines of code? x=5 x=x+5 x=y+5 y=x+5

48

Python Activity 8: Looping Structures – WHILE Loops c.

Replace the operator ‘+=’ with the following shortcut operators and execute the code. Explain what each operator does. -= _________________________________________________________ *=

10.

_________________________________________________________

Enter and execute the following code:

 bonus = 25 salary += bonus  print(“Total salary:”, salary)

11.

a.

What is the output of the preceding code? Is it what you expected?  ________________________________________________________________________

 b.

Edit the code so that it produces valid output.  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________

c.

As a result of correcting this code segment, what is needed in order for the shortcut operators to work properly?  _______________________________________________________________________

d.

Is the following line of code valid: 23 += total? Why or why not?  ________________________________________________________________________

The following code should print the numbers beginning at 100 and ending with 0. However it is missing a line of code. Add the missing code, using the shortcut operator. Indicate where the code belongs.

countdown = 100  while countdown > 0:  print(countdown)  print(“Done!”)

 ________________________________________________________________________  12.

Enter and execute the following code:

doAgain = "y"  while doAgain == "y":  word = input("Enter a word:")  print("First letter of " + word

+ " is " + word[0])

doAgain = input("Type ‘y’ to enter another word and anything

else to quit.")  print("Done!") a.

What does the program do?  ________________________________________________________________________

 b.

What is the name of the variable used to store the user’s input? ____________________ 

c.

In the print statement, what does word[0]represent? ___________________________

49

Python Activity 8: Looping Structures – WHILE Loops d.

If you changed 0 to 1 in word[0]in the print statement above, what is printed?  ________________________________________________________________________

e.

When does the program end?

_____________________________________________

A sentinel-controlled while loop is a loop that repeats the loop body until the user enters a prespecified value.

g.

h.

Why is the loop in this program is an example of a sentinel control loop?  ________________________________________________________________________ Examine the print statement in this program:

 print("First letter of " + word

+ " is " + word[0])

What is the purpose of the “+” as part of the argument in the print statement? What happens if you replace the “+” with a “,”?  ________________________________________________________________________  ________________________________________________________________________ 13.

Examine the code below. name = “Simone” cost = 3.56 numApples = 89 What type of data is stored in each variable: (integer, floating point, or string) name –  __________________________ cost –  __________________________ numApples –  __________________________ A variable that can store only the values True and False is called a Boolean variable.

14.

Given the assignment statement: foundCost = False What value is stored in the variable foundCost? ________________________________ What type of data is stored in foundCost?

15.

________________________________

Enter and execute the following code:

a.

What type of variable is ‘doAgain’? 

50

_______________________________________

Python Activity 8: Looping Structures – WHILE Loops  b.

What does the program do?  ________________________________________________________________________  ________________________________________________________________________

c.

What does the following line of code do?

 maxNum1 = max(num1, num2, num3, num4)  ________________________________________________________________________ d.

Experiment with the arguments in the max() function in the program to determine if the function must have four arguments. Demonstrate your answer.  ________________________________________________________________________  ________________________________________________________________________

e.

What does the following code in the program do? if another != 'y': doAgain = False  ________________________________________________________________________

Application Questions: Use the Python Interpreter to check your work

1.

Write a code segment that prompts the user for an even number. As long as the number is not even, the user should be given a message and prompted again for an even number.  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________

2.

Write code segment that prompts the user for a letter from ‘a -z’. As long as the character is not  between ‘a-z’, the user should be given a message and prompted again for a letter between ‘a -z’.  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________

3.

Complete the following program:

 ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________ 

51

Python Activity 8: Looping Structures – WHILE Loops Notes and Questions  Make note of any questions you have about Activity 8 on this page.

52

Name: _______________________________________ Partners: ________________________________ Python Activity 9: Looping Structures: FOR Loops “Another form of loops”

Learning Objectives Students will be able to: Content: Explain the difference between while loop and a FOR loop Explain the syntax of a FOR loop Explain how to use the range() function in a FOR loop Explain an accumulator in a FOR loop  Process: Write code that includes  FOR loop Write code that uses use FOR loops within functions Prior Knowledge Python concepts from Activities 1-8 Understanding of flowchart input symbols Further Reading Transitioning from Visual Logic to Python: Chapter 9 Critical Thinking Questions: 4. Enter and execute the following two Python programs.

WHILE LOOP -- Python Program

FOR LOOP – Python Program

a. What is the output for each program?  ___________________________________________________________________________  b. Both programs produce the same output. Which code fragment is more concise?  ___________________________________________________________________________ The Python predefined range() function is used to define a series of numbers and can be used in a FOR loop to determine the number of times the loop is executed. .

2.

Enter and execute the following code fragments and state the output: for x in range(5): a. print(x, end=” “)  ________________________________  b.

for x in range(1,5): print(x, end=" ")

 ________________________________

53

Python Activity 9: Looping Structures: FOR Loops c.

3.

for x in range(3,20,2): print(x, end=” “) 

___________________________

d.

numIterations = 6 for x in range(numIterations): print(x, end=” “)  ___________________________

e.

numIterations = 6 for x in range(1, numIterations+1): print(x, end=” “)  ___________________________

After examining the five code fragments in #2, explain how the range() function works. Include an explanation of the arguments.  _____________________________________________________________________________  _____________________________________________________________________________  _____________________________________________________________________________  _____________________________________________________________________________ In a FOR loop you can include a list of values in place of the range() function.

4.

Enter and execute the following code. for x in [3,6,9,12,15,18]: print(x, end=” “) a.    b.

5.

Rewrite this code using the range() function.  ________________________________________________________________________  ________________________________________________________________________ Why would you use the range() function when you could just list the numbers?  _____________________________________________________________________  _____________________________________________________________________  _____________________________________________________________________

As you learned in Activity 8, every loop structure requires three actions. Explain how these actions are implemented in the following Python FOR loop.

for x in range(1,5): print(x, end=" ") a.

 Initialize a variable used in the test condition;  ________________________________________________________________________

 b.

 Include a test condition that causes the loop to end when the condition is false:  ________________________________________________________________________

c.

Within the loop body, update the variable used in the test condition:  ________________________________________________________________________

54

Python Activity 9: Looping Structures: FOR Loops 6.

Read through the code and determine what it does.

favorite = input("Enter your favorite ice cream flavor: ") for x in range(1,5):  print(str(x) + “.”, favorite, end="\t") a.

Explain what you think the program does.  _____________________________________________________________________  _____________________________________________________________________  _____________________________________________________________________

 b.

Enter and execute the code to determine if you were correct. What does the program actually do? Provide a detailed explanation.  _____________________________________________________________________  _____________________________________________________________________  _____________________________________________________________________  _____________________________________________________________________

c.

Explain the use of the str() function in the print statement. Why is it needed?  _____________________________________________________________________  _____________________________________________________________________  _____________________________________________________________________

7.

Complete the arguments in the following range function so that the code prints the even numbers between 100 and 200 inclusive.

for x in range(_____________________________):  print(x) 8.

Complete the arguments in the following range function so that the code prints: 5 4 3 2 1 0.

for x in range(______________________________):  print(x) An accumulator is a variable that stores the sum of a group of values. 9.

Examine the following code segment. total = 0 for x in range(5): number = int(input("Enter a number: ")) total += number print("The total is:",total) a.

Why is the variable total initialized to 0 in the first line of code?  ________________________________________________________________________  ________________________________________________________________________

 b.

Explain what the following code does:

number = int(input("Enter a number: "))  ________________________________________________________________________  ________________________________________________________________________

55

Python Activity 9: Looping Structures: FOR Loops

10.

c.

total += number Explain what the following code does:  ________________________________________________________________________  ________________________________________________________________________

d.

How many numbers does the program prompt for?

e.

What is the accumulator in the code segment?  ________________________________________________________________________

__________________________

Is it better to use a FOR loop when you know the number of times the loop should be executed or when you do not know? Explain your answer.  ______________________________________________________________________________  ______________________________________________________________________________

Application Questions: Use the Python Interpreter to check your work

1.

Write a code segment using a FOR loop that prints multiples of 5 from 5 to 500.  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________

2.

Complete the program on the following page. The program should: Display five addition facts, one at a time, and allow the user to answer them. Provide the correct answer if user enters incorrect answer. Print a congratulatory answer, if the answer is correct. Keep track of the number of problems the user answers correctly. Prints a special message, if the user gets all five problems correct. Fill in the missing code; comments (also written below) indicate location of missing code. # include the required import statement  ______________________________________________________________________________ # include a FOR loop that prints the numbers from 10 to 0  ______________________________________________________________________________ # Assign a random number between 1 and 10 to num1 and num2  ______________________________________________________________________________ # Write the test condition to determine if the user’s # answer is equal to the sum of the two numbers  ______________________________________________________________________________ # Write the line of code to increment the variable # that is keeping track of the number of correct answers.  ______________________________________________________________________________ # Print the addition fact and include the correct answer.  ______________________________________________________________________________

56

Python Activity 9: Looping Structures: FOR Loops # Write the test condition to determine if the user answered # all the questions correctly  ______________________________________________________________________________ # Write the code to call the function that prints the rocket  ______________________________________________________________________________

57

Python Activity 9: Looping Structures: FOR Loops Notes and Questions  Make note of any questions you have about Activity 9 on this page.

58

Name: _______________________________________ Partners: ________________________________ Python Activity 10: Files and Nesting Looping Structures “Alternative input and loops inside loops”

Learning Objectives Students will be able to: Content: Explain how to open a text file for reading and for writing Explain the difference between the read() and readline() functions Explain the purpose of the str() function. Explain the effect of the arguments of the range function when reading data from a file. Explain the purpose of the rstrip(), open(), close(), and write() functions Explain the difference between writing and appending to a file Read and write nested FOR loops Identify inner and outer loops  Process: Write code that opens, writes to and closes a file Write code that opens, reads from and closes a file Write code that uses a nested FOR loop Prior Knowledge Python concepts from Activities 1-9 Further Reading Transitioning from Visual Logic to Python: Chapter 10 Critical Thinking Questions: In Python, you can access data from a text file as well as from the keyboard. You can create a text file in any text editing tool. You should only have one data item per line in the file.

5.

Create a text file named sports.txt and enter the sports listed below, one word per line. Enter and execute the Python program. Be sure the saved program is in the same folder as the text file.

Python Program

sports.txt file

59

Python Activity 10: Files and Nesting Looping Structures a.

What does the program do?  _______________________________________________________________________

 b.

Explain the purpose and syntax of the first line of code. What does the ‘string argument’ for the function open represent?

 _______________________________________________________________________

2.

c.

Replace the function read()   with the function readline(). Execute the program again. What happens?  _______________________________________________________________________  _______________________________________________________________________

d.

Explain the difference between the two functions: read() and readline().  _______________________________________________________________________  _______________________________________________________________________

Enter and execute the following code.

a.

Explain the format and content of the output.  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________

 b.

How does the output from this programs differ from the output of the program that used the “read()” function? What caused the difference?  ________________________________________________________________________  _______________________________________________________________________

c.

What is the subtle difference in the output if the following print statement replaced the one above? Which is better?  ________________________________________________________________________

d.

What does str(index) do in the program above? Why is the str () function necessary?  ________________________________________________________________________  ________________________________________________________________________

e.

What happens when you change the arguments in the range() function to 1,10?  _______________________________________________________________________

f.

What happens when you change the arguments in the range() function to (0, 30)?  _______________________________________________________________________

60

Python Activity 10: Files and Nesting Looping Structures g.

What do the results fr om “f.” and “g.” tell you about the arguments of the range() function when you are using it in a FOR loop to read data from a file?  ________________________________________________________________________  ________________________________________________________________________ The purpose of the rstrip() function is rather subtle. rstrip() returns a copy of the string after all characters have been stripped from the end of the string (default whitespace characters, EOL characters, and newline characters).

3.

The following program is slightly different from the program in #2. Enter and execute the  program.

a.

Compare the output from this program to the output in the previous program. What is the difference?  ________________________________________________________________________

 b.

What code caused the difference in the output?  ________________________________________________________________________

c.

In this example the rstrip() function strips the newline character from the string that is read from the file. Why is the newline character attached to the end of the string?  ________________________________________________________________________

d.

Does the rstrip() function contain any arguments? How does it know what string to act upon?  ________________________________________________________________________

e.

lstrip() is a similar function. What do you think it does?

 ____________________________________________________ 4.

The following program is slightly different from the program in #3. Enter and execute the  program.

a.

What does the program display?  ________________________________________________________________________  ________________________________________________________________________

 b.

How many functions are used in this program? _________________________________

c.

Two functions use what is known as dot(.) notation. What are the two functions ?  ________________________________________________________________________

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Python Activity 10: Files and Nesting Looping Structures d.

5.

Examine the output and explain what the len() function does.  ________________________________________________________________________

Enter and execute the following program:

a.

What output appears on the screen?  ________________________________________________________________________

 b.

What does the program do?  ________________________________________________________________________

c.

Locate the file studentInfo.txt on your computer. The file is stored in the same folder as the program. What is stored in the file?  ________________________________________________________________________

d.

What is the purpose of “w” in the following line of code?

 ________________________________________________________________________ e.

Did you create the file: studentInfo.txt before you included it in the code? ___________

f.

Execute the program again using different input. Open the studentInfo.txt file. What is in the file? Is the data from the first program execution still there?  ________________________________________________________________________

g.

Change the ‘w’ to ‘a’ in the open() function. Execute the program again with different input. Examine the student Info.txt file. What did ‘a’ as an argument in the open() function do? What word do you think ‘a’ represents?  ________________________________________________________________________  ________________________________________________________________________

h.

Notice the new function – write(). How many arguments does the write function have?  ________________________________________________________________________

i.

How does the write() function know what file to write to?  ________________________________________________________________________

 j.

What line of code closes the file? Where is the line of code positioned in the program?  ________________________________________________________________________  ________________________________________________________________________

62

Python Activity 10: Files and Nesting Looping Structures k.

Revise the program so that the user can enter three names during one execution of the  program. You may need to change the order of some of the code.  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________ A loop within another loop is known as a nest loop. Proper indentation is essential for the loops to work properly..

6.

6.

Enter and execute the following code:

a.

What does the program display?  ________________________________________________________________________

 b.

How many FOR loops are in this code? Is one loop completely executed before the next loop begins? What do you call this type of loop?  ________________________________________________________________________  ________________________________________________________________________

c.

How many times is the following line of code executed in the program? ______________

d.

In the program listed at #6, above, label the inner loop and the outer loop.

e.

What does the inner loop do?  ________________________________________________________________________

f.

What does the outer loop do?  ________________________________________________________________________

If you were asked to created a Python program that displayed the adjacent rectangle, you could easily do it with a set of print statements or a FOR loop and a print statement. We will go through several steps to create a program that will print similar output but allows the user to determine the length and width of the figure when they execute the program.

63

Python Activity 10: Files and Nesting Looping Structures

7.

a.

Create a code segment that prompts the user for a number between 1 and 10 and then  prints that many asterisks (*) on one line. Use a FOR loop.  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________

 b.

You want to create several lines of asterisks. Revise the code in “a.” to also prompt the user for how many lines to print. Use an “outer” loop to print that many lines of asterisks.  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________

c.

Edit the program so that it prints numbers instead of asterisks. Write the line of code that was changed.  ________________________________________________________

Examine the following code and determine the output. Indicate the changes in memory as the program is executed. Assume the user input is 5.

Variable height row column

Memory

Application Questions: Use the Python Interpreter to check your work 1. Create a text file that contains 10 numbers between 50 and 100. Write a program that reads the numbers from the file and totals the numbers. The program should print all the numbers and display the total when all the numbers have been added together. (Warning! The input from the file will be considered a string. Be sure to convert the input to int or float –  just as you do when numbers are entered from the keyboard.)  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________

64

Python Activity 10: Files and Nesting Looping Structures 2.

Revise the following program. Allow the user to enter the name of the file and use the input to open the file.

 ______________________________________________________________________________  ______________________________________________________________________________ 3.

Create a Python program that prompts the user for a number and then prints an inverted right triangle containing that many rows similar to the output to the right.

 ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________  ______________________________________________________________________________

65

Python Activity 10: Files and Nesting Looping Structures Notes and Questions  Make note of any questions you have about Activity 10 on this page.

66

Name: _______________________________________ Partners: ________________________________ Python Activity 11 Part A: Lists “More versatile than arrays -- lists”

Learning Objectives Students will be able to: Content: Define a list Identify elements of a list Explain the purpose of positive and negative indexes in a list . Explain how to access individual elements of a list Explain how the following functions are used with lists: append(), insert(), remove(), count(), index() Explain how to replace an item  Process: Write code that prints a list Write code that edits a list  –  add, remove, and insert items Prior Knowledge Python concepts from Activities 1-10 Further Reading Transitioning from Visual Logic to Python: Chapter 11 pp. 95-101 Critical Thinking Questions: A sequence is an object that stores multiple data items in a contiguous manner. Two types of sequences are strings and lists. Each value stored in a list is called an element.

6.

Examine the sample lists below.

Sample Lists in Python

a.

How many elements does the list named digits contain?

___________________

 b.

What type of data is stored in each list (String, numeric)? digits list: __________________________________________________________ fruits list: __________________________________________________________ studentData list: ___________________________________________________

c.

How would you define a list?  _______________________________________________________________________  _______________________________________________________________________

67

Python Activity 11 Part A: Lists 2.

The following line of code prints the first element in the digits list.

a.

What value does fruits[3] represent?

_______________________________________

 b.

Enter and type the fruits list and write a line of code that prints the last value.  ________________________________________________________________________

c.

Edit your print statement in ‘b’ so that it prints fruits[4]. What is printed? Why?  ________________________________________________________________________

d.

Edit your print statement so that it prints fruits[-1]. What is printed?  _______________________________________________________________________

e.

Change -1 to -2 in “d.”. What is printed?  _______________________________________________________________________ The number used to locate an element in the list is called an index.

3.

f.

Explain how the positive and negative indexes locate the desired elements.  _______________________________________________________________________  _______________________________________________________________________

g.

What is printed with the following print statement: print(fruits)? How is the information displayed?  _______________________________________________________________________  _______________________________________________________________________

Enter and execute the following code:

a.

What is the output?  _______________________________________________________________________  _______________________________________________________________________

 b.

Explain the first line of code especially the code on the right hand side of the equal sign.  ___   _____________________________________________________________________  _______________________________________________________________________ 

c.

Explain why the second line of code produces the same output as the first line above.  ________________________________________________________________________  _________________________________________________________________ ______

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Python Activity 11 Part A: Lists d.

4.

Add the following line of code to the program:  print(len(mult2)) What is the output? What does the len() function do?  _______________________________________________________________________  _______________________________________________________________________ 

Enter and execute the following code:

a.

What is the output for the second line of code:  ________________________________________________________________________

 b.

Examine the following code. It contains a FOR loop but does not use the range() function. In previous FOR loops the values resulting from the range() function were stored in x during each iteration of the loop.

i. What is being stored in x for each iteration of the loop in the following code?  ________________________________________________________________________ ii. What is the output for this code?  ________________________________________________________________________ c.

What are the similarities and differences between the output for “a.” and “b.”?  _______________________________________________________________________  _______________________________________________________________________

d.

Add each of the following print statements to the code above. What is the output for each statement? Explain the output.

 _______________________________________________________________________  _______________________________________________________________________  _______________________________________________________________________  _______________________________________________________________________

69

Python Activity 11 Part A: Lists 5.

6.

7.

8.

Enter and execute the following code:

a.

Explain what the following line of code does: flowers.append(‘gardenia’)  _______________________________________________________________________  _______________________________________________________________________ 

 b.

Write a line of code that would add the flower lavender to the list.  _______________________________________________________________________

Enter and execute the following code:

a.

Explain what the following line of code does: flowers.insert(2,‘lily’)  _______________________________________________________________________  _______________________________________________________________________ 

 b.

Write a line of code that would place the flower: sunflower at the beginning of the list.  _______________________________________________________________________

Enter and execute the following code:

a.

Explain what the following line of code does: del flowers[2]  _______________________________________________________________________  _______________________________________________________________________ 

 b.

Write a line of code that would delete the last flower in the list.  _______________________________________________________________________

Enter and execute the following code:

a.

Explain what the following line of code does: flowers.remove(‘tulip’)  _______________________________________________________________________  _______________________________________________________________________ 

70

Python Activity 11 Part A: Lists

9.

10.

 b.

Write a line of code that would delete ‘daffodil’ from the list.  ________________________________________________________________________

c.

Edit the code to determine what happens if the same flower appears in the list twice and use the remove()function to remove the word. Does it remove both instances of the word? _________________________________________________________________

d.

Write a line of code that attempts to remove the flower: sweet pea. What happens when the code is executed?  _______________________________________________________________________

Enter and execute the following code:

a.

Explain what the following line of code does: flowers[1]= ‘freesia’  _______________________________________________________________________  _______________________________________________________________________ 

 b.

Write a line of code that would replace ‘daffodil’ with ‘gardenia’.  _______________________________________________________________________

c.

Explain what the following line of code does: flowers[-3]= ‘lily’  _______________________________________________________________________  _______________________________________________________________________

d.

Explain what happens when the following line of code is added to the program: flowers[8]= ‘lily’  _______________________________________________________________________  _______________________________________________________________________

Enter and execute the following code:

71

Python Activity 11 Part A: Lists a.

What is the output of this program?  _______________________________________________________________________  _______________________________________________________________________  _______________________________________________________________________

 b.

Explain the line of code: numY = ballot.count(‘y’) What does the count() function do? How many arguments does it have?  ________________________________________________________________________

c.

Add the following lines of code to the program:

What do the lines print? ____________________________________________________ What does the index() function do? _______________________________________  ________________________________________________________________________ What happens if you replace ‘y’ or ‘n’ with ‘x’? Why does this happen?  _______________________________________________________________________  _______________________________________________________________________

Application Questions: Use the Python Interpreter to check your work

1.

Create a program that prints a given list, prompts the user for a name and average, adds the new information to the list and prints the new list. It should produce output similar to the following:  _______________________________________________________________________  _______________________________________________________________________  _______________________________________________________________________  _______________________________________________________________________  _____________________________________________________________________________  _____________________________________________________________________________  _____________________________________________________________________________  _____________________________________________________________________________  _____________________________________________________________________________  _____________________________________________________________________________  _____________________________________________________________________________  _____________________________________________________________________________

7.

Revise the previous program so that it allows the user to enter the name of a person in the list whose average needs updating and also prompts the user for the new average. The program should then update the list and print the new list. The program should produce output similar to the output on the following page:

72

Python Activity 11 Part A: Lists

 _____________________________________________________________________________  _____________________________________________________________________________  _____________________________________________________________________________  _____________________________________________________________________________  _____________________________________________________________________________  _____________________________________________________________________________  _____________________________________________________________________________  _____________________________________________________________________________

73

Python Activity 11 Part A: Lists Notes and Questions  Make note of any questions you have about Activity 11A on this page.

74

Name: _______________________________________ Partners: ________________________________ Python Activity 11 Part B: List Functions “More versatile than arrays -- lists”

Learning Objectives Students will be able to: Content: Explain how the following functions are used with lists: reverse(), sort(), max(), min() Explain how to use lists with files  Process: Write code that reverses and sorts lists Write code the finds the largest or smallest element of a list Write code that reads from a file into a list Prior Knowledge Python concepts from Activities 1-10 and 11_1 Further Reading Transitioning from Visual Logic to Python: Chapter 11 pp. 101-109 Critical Thinking Questions:

1.

Enter and execute the following code:

a. What does the code print?  ___________________________________________________________________________  ___________________________________________________________________________  b. What does the reverse() function do?  ___________________________________________________________________________ 2.

Revise the program in #1 to test each of the following functions. a. sort function: .sort() Write the revised line of code here: ___________________________________________ Does the function make a permanent change to the list? __________________________ Does the function need to be called within an assignment statement? _____________  b. max  function: max() Write the revised line of code here: _______________________________________ Explain the difference between the call to this function and the call to the sort function.  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________

75

Python Activity 12: More about Lists and Strings Does the function need to be called within an assignment statement? c. mi n  function: min() Write the revised code here:

_____________

_____________________________________________

Is the call to this function similar to the call to the sort function or the max function?  _______________________________________________________________________ Does the function need to be called within an assignment statement?

____________

The member operation determines if a given item is an element of a list. The operation returns True if the item is an element of the list and False otherwise. Syntax: in .

3.

The following program demonstrates the member operation for a list. Enter and execute the  program:

a.

Circle the line of code that uses the member operation.

 b.

Edit the program so that if the number the user entered is not in the list, it is added to the list. Print the list again to be sure the number is added to the list. Here is some sample output:

 ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________

76

Python Activity 12: More about Lists and Strings c. Suppose the program prompted the user for two numbers and stored them in the variables  guess1 and guess2. Write the code segment that would pri nt “Super guess!” if the user entered two numbers in the list.  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________ 4.

Let’s write a program –  step by step -- that generates 100 numbers between 1 and 500 and puts them in a list, prints the numbers, sorts the numbers, reverses the order of the numbers, determines the number of times a given number is in the list and prints the largest and smallest number. a. Create an empty list to store the number  __________________________________  b. Create code to generate 100 numbers  between 1 & 500 store them in the list  __________________________________  __________________________________  __________________________________ c. Create the code to print the list without the  brackets. Create a separate function for this since you will be printing the list several times.  __________________________________  __________________________________  __________________________________  __________________________________  __________________________________  __________________________________  __________________________________  __________________________________  __________________________________ d. Write the code that sorts and then reverses the numbers. Print the code after it is sorted and after the numbers are reversed.  __________________________________  __________________________________  __________________________________  __________________________________ e. Does the order of these two lines of code matter? ________________________

77

Python Activity 12: More about Lists and Strings f.

Write the code that prompts the user for a number between 1 and 500 and prints how many times that number is in the list. If the number is not in the list print the message: “Sorry, your number is not here!”  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________

g. Print the largest and smallest number.  ___________________________________________________________________________  ___________________________________________________________________________ h. Enter and execute the code from a-e. be sure that it executes properly. List one sample output.  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________ i.

To make the numbers appear in columns, replace the print statement in the print function with the following line of code: print("%3d" %x, end=" "). What causes the change in output format?  ___________________________________________________________________________

5.

Enter and execute the following code. What does the program do?

6.

 ______________________________________________________________________________   ______________________________________________________________________________ Add the following code to the program above:

a.

What does the program do once this code is added?  ________________________________________________________________________  ________________________________________________________________________

 b.

Explain the following code:  ________________________________________________________________________

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Python Activity 12: More about Lists and Strings c.

Explain what the following line of code does:  ________________________________________________________________________

d.

Add a final line of code to the program that prints the list.  ________________________________________________________________________

Application Question: Use the Python Interpreter to check your work

Complete the missing sections of the following program in the Python interpreter. Most of the code is missing. Where there is code, comments are needed. First create a text file with several numbers, one on a line.

79

Python Activity 12: More about Lists and Strings

Notes and Questions  Make note of any questions you have about Activity 11B on this page.

80

Name: _______________________________________ Partners: ________________________________ Python Activity 12: More about Lists and Strings “Lists and Strings and Functions and more….”

Critical Thinking Questions: Learning Objectives Students will be able to: Content: Explain how to send a list as an argument to a function Explain the purpose of the following functions: isalpha(), isdigit(), isspace(), upper(), lower() Explain what is meant by the fact that “Strings are immutable.” Demonstrate the use of slicing with strings and lists.  Process: Write code that uses the following functions: isalpha(), isdigit(), isspace(), Write code that uses slicing to access elements of a list Prior Knowledge Python concepts from Activities 1-11_2 Further Reading Transitioning from Visual Logic to Python: Chapter 12

1.

2.

At the end of the previous activity you created a function to print a list and passed the list to the function. Here is another program that includes a function that takes a list as an argument. Enter and execute the code.

a.

What is the name of the function defined in this program?

 b.

What does the function do?  ________________________________________________________________________

Enter and execute the following code.

81

___________________

Python Activity 12: More about Lists and Strings

3.

4.

a.

Execute the program with at least five different types of input that include just letters, just numbers, letters, numbers and other characters. Examine the output for each input. What does the program do?  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________

 b.

What does the isalpha() function do?  ________________________________________________________________________  ________________________________________________________________________

Enter and execute the following code.

a.

Execute the program with at least five different types of input. Examine the output for each input. What does the program do?  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________

 b.

What does the isdigit() function do?  ________________________________________________________________________  ________________________________________________________________________

Enter and execute the following code.

a.

What does the program do?  ________________________________________________________________________  ________________________________________________________________________

82

Python Activity 12: More about Lists and Strings  b.

5.

What does the isspace() function do?  ________________________________________________________________________  ________________________________________________________________________

Enter and execute the following code:

c. Execute the program with the following input and examine the corresponding output. cmsc190 __________________________________________________________ Cmsc190

__________________________________________________________

CMSC180

__________________________________________________________

CMSC190

__________________________________________________________

d. What does the upper() function do?  __________________________________________________________________________  __________________________________________________________________________ c. Use the lower() function instead of the upper() function in the program above. Revise the line of code so that it still produces the same output. Execute the program again with the data listed in ‘a’. (Write the revise code below.)  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________  ___________________________________________________________________________ 6.

Examine the following code:

a.

 b.

What do you think the program prints?  _______________________________________________________________________  _______________________________________________________________________ Enter and execute the code. Does the program do what you thought it did?  _______________________________________________________________________

c.

What would you think the code word[0] = ‘c’ should do? What does it actually do?  _______________________________________________________________________

d.

“Strings are immutable.” From the output you saw when you executed this program, what do you think this statement means?  _______________________________________________________________________ 

83

Python Activity 12: More about Lists and Strings Slicing is a technique available in Python that allows you to access parts of lists or strings. You can select multiple elements of a list or string. Syntax: [indexOfFirstItem : indexAfterLastItem].

7.

In this section we are going to try to access parts of a string using slicing. Enter and execute the following code. Examine the syntax of the code. It uses slicing to access parts of a string.

a.

What is the output for each print statement in the program?  _______________________________________________________________________  _______________________________________________________________________  _______________________________________________________________________  _______________________________________________________________________  _______________________________________________________________________  _______________________________________________________________________

 b.

The first three print statements should be familiar. What does the fourth print statement do? Explain the meaning of [0:13]. ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________

   

c.

 ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________ 

 

d.

 

8.

What does the following print statement do? Explain the meaning of [16:27].

What does the following print statement do? Explain the meaning of [28:].  ________________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________ 

Finally, examine slicing using lists. Enter and execute the following program.

84

Python Activity 12: More about Lists and Strings a.      b.   c.   d.   e.  

What is the output of each print statement in the program?  ________________________________________________________________________  ________________________________________________________________________  _______________________________________________________________________  ________________________________________________________________________ Explain what the following code does.  ________________________________________________________________________  ________________________________________________________________________ Explain what the following code does:  ________________________________________________________________________  ________________________________________________________________________ Are lists immutable? Explain your answer.  ________________________________________________________________________  ________________________________________________________________________ Explain what the following code does:  ________________________________________________________________________  ________________________________________________________________________

Application Questions: Use the Python Interpreter to check your work

1.

Create a list named “Days” that includes all the days of the week. Print the list.  ______________________________________________________________________________

2.

Create a line of code that uses slicing to print the last three days in the list “Days” which you created in question 1.  ______________________________________________________________________________

3.

Create a list named “Vowels” that includes the vowels ‘a’, ‘e’, ‘i’, ‘o’, ‘u’.  ______________________________________________________________________________

4.

Use the code in question 3, and create a program that analyzes a use r’s input. Complete the following steps: a. Create code that prompts the user for a vowel.  ________________________________________________________________________  b.

Create code to determine if the user input is a vowel. If so, congratulate them.  _______________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________

c.

Create code that determines if it is a letter, but not a vowel and prints a message that indicates that.  _______________________________________________________________________  ________________________________________________________________________  ________________________________________________________________________

85