Lab 3c — Lists

Shopping List

10 minutes

In shopping_list.py, you will find a program that is supposed to let you enter a list of items for a grocery list. You finish entering items by entering a blank line (just pressing enter). But this is what it does if you run it:

Enter an item: milk
Enter an item: eggs
Enter an item: butter
Enter an item:
['']

(1) Working with a partner, use the debugger to step through the code and see what is going wrong.

(2) With your partner, fix the code so it works properly.

(3) Discuss what bugs you found and how you fixed them.

Places Visited

15 minutes

Use the file places_visited.py to write a program that asks you to enter places you have visited, then places you want to visit, and then prints those out. You finish entering places by entering a blank line (just pressing enter). The output should look like this:

Enter a place you have visited: Oregon
Enter a place you have visited: Washington, D.C.
Enter a place you have visited: Italy
Enter a place you have visited:
Enter a place you want to visit: Maine
Enter a place you want to visit: Grand Canyon
Enter a place you want to visit: Hawaii
Enter a place you want to visit:
I have visited:
- Oregon
- Washington, D.C.
- Italy
I want to visit:
- Maine
- Grand Canyon
- Hawaii

Notice how the code you would write to get the first and second lists are nearly identical. In fact, they are the same except for the prompt given to the input function.

Notice also how both lists are printed out with the same format, just with different headers. We can follow the same principle as we did for getting the lists of places and write a single function that can print any list of items.

The starter code looks like this:

def get_list(prompt):
    responses = []
    while True:
        response = input(prompt)
        if response == '':
            break
        responses.append(response)
    return responses


def print_list(items):
    for item in items:
        print(f'- {item}')


def main():
    # Write code here
    pass


if __name__ == '__main__':
    main()

Use the provided get_list and print_list functions to implement this activity.

Functions like get_list and print_list, that can be easily customized for a variety of contexts through a parameter, are called generic functions.

Writing and using generic functions is an important skill in programming. Whenever you see that your code needs to do essentially the same thing more than once, consider writing a generic function with a parameter that controls the difference (for example, the prompt used by input in the get_list function above).

Discuss how you would use get_list and print_list with a TA, and then write your code.

Puppy Libs

15 minutes

Use the file puppy_libs.py to write a program that asks you to enter a series of adjectives followed by a series of verbs ending in ing. Both lists will end with a blank line. The program then prints out The puppy is {word}! for each adjective and then each verb. It ends by printing The puppy is taking a nap.

Here is some sample input and output:

Enter an adjective: soft
Enter an adjective: cute
Enter an adjective: drooly
Enter an adjective:
Enter a verb ending in "ing": playing
Enter a verb ending in "ing": jumping
Enter a verb ending in "ing": barking
Enter a verb ending in "ing": eating
Enter a verb ending in "ing": laughing
Enter a verb ending in "ing":
The puppy is soft!
The puppy is cute!
The puppy is drooly!
The puppy is playing!
The puppy is jumping!
The puppy is barking!
The puppy is eating!
The puppy is laughing!
The puppy is taking a nap.

The starter code looks like this:

def main():
    # Write code here
    pass


if __name__ == '__main__':
    main()

Start by making a list of the functions you will call inside of main() to decompose the problem. Be sure to write a generic function for getting each list of words:

Discuss the functions you would use with the TA, and then write your code.

Afer you write the code, discuss with the TA:

• What does this program have in common with the places visited one?