10. Exercises

  1. Write a program that allows the user to enter a string. It then prints a table of the letters of the alphabet in alphabetical order which occur in the string together with the number of times each letter occurs. Case should be ignored. A sample run of the program might look like this:

    Please enter a sentence: ThiS is a String with Upper and lower case Letters.
    a  3
    c  1
    d  1
    e  5
    g  1
    h  2
    i  4
    l  2
    n  2
    o  1
    p  2
    r  4
    s  5
    t  5
    u  1
    w  2
    $
    
  2. Write a program that will function as a grade book, allowing a user (a professor or teacher) to enter the class roster for a course, along with each student’s cumulative grade. It then prints the class roster along with the average cumulative grade. Grades are on a 0-100 percentage scale. Use 2 lists (grades and students) and the enumerate function in your solution.

    A test run of this program would yield the following:

    # this is the first batch of input the user would enter
    Chris
    Jesse
    Sally
    
    # this is the second batch of input the user would enter
    Grade for Chris: 90
    Grade for Jesse: 80
    Grade for Sally: 70
    
    # below is what your program should output
    Class roster:
    Chris (90.0)
    Jesse (80.0)
    Sally (70.0)
    
    Average grade: 80.0
    
  3. Implement the functionality of the above program using a dictionary instead of a list.

  4. Make a dictionary where the key is a worker’s name, and the value is a list where the first element is the clock in time, second element is the clock out time, and the third element is the total hours worked that day. Each worker’s list starts at [0, 0, 0]. Create functions for clock_in and clock_out.

    • clock_in takes the dictionary of workers, the name of the worker, and the clock in time as parameters. When the worker clocks in, enter and save their clock in time as the first element in the associated list value.
    • clock_out takes the same parameters, but with a clock out time instead of clock in time. When the worker clocks out, enter and save their clock out time and calculate the hours worked for that day and store it as the third element in the list.

    To make this program a little easier, we’re entering the clock in and clock out times as integers. As a bonus mission, try adding the times as strings representing the 24 hour clock (e.g., "08:00"), and then figure out how to calculate the time worked. And you can do this exercise either by aliasing or copying the dictionary.

  5. Here’s a table of English to Pirate translations:

    English Pirate
    sir matey
    hotel fleabag inn
    student swabbie
    boy matey
    madam proud beauty
    professor foul blaggart
    restaurant galley
    your yer
    excuse arr
    students swabbies
    are be
    lawyer foul blaggart
    restroom th’ head
    my me
    hello avast
    is be
    man matey

    Write a program that asks the user for a sentence in English and then translates that sentence to Pirate.

  6. Give the Python interpreter’s response to each of the following from a continuous interpreter session:

    1. >>> d = {'apples': 15, 'bananas': 35, 'grapes': 12}
      >>> d['bananas']
      
    2. >>> d['oranges'] = 20
      >>> len(d)
      
    3. >>> 'grapes' in d
      
    4. >>> d['pears']
      
    5. >>> d.get('pears', 0)
      
    6. >>> fruits = d.keys()
      >>> sorted(fruits)
      >>> print(fruits)
      
    7. >>> del d['apples']
      >>> 'apples' in d
      

    Be sure you understand why you get each result. Then apply what you have learned to fill in the body of the function below:

Weekly Graded Assignment

Write a sort_contacts function that takes a dictionary of contacts as a parameter and returns a sorted list of those contacts, where each contact is a tuple.

The contacts dictionary that will be passed into the function has the contact name as its key, and the value is a tuple containing the phone number and email for the contact.

contacts = {name: (phone, email), name: (phone, email), etc.}

The sort_contacts function should then create a new, sorted (by last name) list of tuples representing all of the contact info (one tuple for each contact) that was in the dictionary. It should then return this list to the calling function.

For example, given a dictionary argument of:

{"Horney, Karen": ("1-541-656-3010", "karen@psychoanalysis.com"),
"Welles, Orson": ("1-312-720-8888", "orson@notlive.com"),
"Freud, Anna": ("1-541-754-3010", "anna@psychoanalysis.com")}

sort_contacts should return this:

[('Freud, Anna', '1-541-754-3010', 'anna@psychoanalysis.com'), ('Horney, Karen', '1-541-656-3010', 'karen@psychoanalysis.com'), ('Welles, Orson', '1-312-720-8888', 'orson@notlive.com')]