Activity 2-1

February 26, 2013

Task 1: Python Expressions and Assignments

  1. Write an expression that averages the numbers 2, 5, and 9. Make sure you get a decimal number (a float).
  2. Assign the list of numbers [2,5,9] to a variable called myList. Write an expression that averages the elements of myList.
  3. Assign the string "2 5 9" to a variable called myString. Using indexing, write an expression that just returns "2". Do the same for "5" and "9".
  4. Add the three expressions you wrote in the previous step together. What do you get? Why?

Task 2: Python Functions

Consider the following Python program. The numbers to the left of the green line are just line references, and not part of the program; you wouldn't type them if you were writing this program yourself.

y = 10
x = y + 5

def addOne(t):
  y = t + 1
  return y

z = addOne(x)

Starting at Line 1, go through the program and write down the variable table (like we just did in class). What does z output in Line 9? What does y output in Line 10?

If we have time...

Task 3: Splitting a String and Working with Files

  1. The split function, without an input argument, splits a string on any whitespace (including spaces, newlines, tabs, etc.). Use the expression fileString.split(<delimiter>) to split on different delimiters by passing a string delimiter as input to the split function. Observe what happens when the delimiter is:
    • "\n"
    • "a"
    • "Sarah"
  2. In, write a function called readShel that opens the poem and returns a list of words. We have already written each line in class already — you just need to put them together.

Task 4: Counting the Number of Words in Moby Dick

Download and save MobyDick.txt. In, write a readMobyDick() function and a countWordsInMobyDick() function. Note that only a few things change from the Shel functions.

Be sure to save this python file! It will be useful for the next class.