Activity 21 - What else? 🤔

The exam approaches. What else would you like to have practice with? What thing in python do you struggle with the most? Pick one or more options below. We can do any of these together in class. You can also pick ANY of the previous in-class activities.

Create a file exam2-practice.py and save to your cs100/ch5 folder.

Option A: Manipulating strings

• Use the repetition operator to print out “cool.” 7 times
• Break up a sentence into a list of words
• Find the number of occurences of the word ‘the’ in a given string.
• Use substring operator to print “awesome” from “CS100 is super awesome”.
• Use index operator to print “i” from the same string.

Option B: Encryption/decryption

• Use a substitution cipher to encode & decode a string (see activity 15)
• Use a transpotition cipher to encode & decode a string (see activity 15)
• Use a caesar cipher to encode & decode a string (see activity 16)

Option C: Lists

• Use a for loop to create a list listA that contains 10 random numbers.
• Use a list comprehension to create a list listB that contains 10 random numbers
• Print “found it” if 1 is in the list
• Print the list sorted in ascending order.
• Use a while loop to add values input from the user into a list.

Option D: Dictionaries

• Create a dictionary containing the name and value of US denominations (penny, nickel, etc.)
• Write a function that merges two dictionaries
• Add a value to a dictionary
• Use a while loop to add (key, value) pairs input from the user into a dictionary.

Option E: Statistics

• Consider the list a=[1, 2, 3, 4, 1, 2, 3, 1, 3, 1, 2, 4, 5, 1, 2, 3, 6, 7, 3, 3, 1]. Compute the mean, median, and mode, and calculate the frequency distribution.
• Write code that sums up all the positive numbers entered by the user. When the user enters a negative number, the program displays the sum of the positive numbers and how many numbers were entered. Hint: Use a while loop to check if the number is positive or negative. Note that the negative number doesn’t contribute to the sum. Next, compute the mean of the positive numbers. An example execution is below:

  Enter next number (negative number to stop): 5
  Enter next number (negative number to stop): 10
  Enter next number (negative number to stop): 3
  Enter next number (negative number to stop): -1
  Sum of all positive numbers:  18
  

• See activity to plot frequency distribution
• See activity to compute correlation

Option F: Reading/writing to files

• Create a file called numbers.txt and write to it the first 100 numbers using a while loop
• Create a file called scores.txt. Use a while loop to prompt the user to type in student names and corresponding scores to write to the file. End the program when the user types q.
• Read from the previously created file to compute the average of student scores.
• Save the rainfall.txt file locally. Count how many lines are in the file.

Option G: Reading from internet

• Read (but do not download) the file from http://csweb.wooster.edu/hguarnera/cs100/assignments/rainfall.txt. Output the contents of the page to the terminal decoded in UTF-8 format.

Option Z: Nothing is hard.

Cool beans. Pick 5 questions from above and complete them independently.

How to submit

Save your working python file and submit to Moodle.