Lecture 10 — Exercises

Solutions to the problems below must be sent to Submitty for grading. A separate file must submitted for each problem. Since the disscusion of loops and lists is so important and because you do not have lab next week, this set of exercises is somewhat longer than normal. Solutions must be submitted by 4 pm on Fridday, October 7.

  1. Submit a text file showing the output of the following code:

    L1 = [ 1, 5, [5, 2], 'hello' ]
    L2 = L1
    L3 = L1.copy()
    L2.append( 4 )
    L1.append( 3 )
  2. Submit a text file showing the output of the following code

    def head_and_tail(L):
        from_back = L.pop()
        from_front = L.pop(0)
    L1 = [ [1, 2], 3 ]
    L3 = L1.copy()
    L2 = L1
    L2[-1] = 5
    print(L1[0], L1[-1], len(L1))
    print(L2[0], L2[-1], len(L2))
    print(L3[0], L3[-1], len(L3))
  3. The solution to this problem and the two that follow should start with the assignment

    co2_levels = [ 320.03, 322.16, 328.07, 333.91, 341.47, \
                   348.92, 357.29, 363.77, 371.51, 382.47, 392.95 ]

    Write a Python program that prints the number of values that are greater than the average of the list. For this you may use Python’s sum and len functions and you must use a for loop. Do NOT use a range, however, and do not use indexing.

    Your output should simply be:

    Average: 351.14
    Num above average: 5
  4. Suppose we discovered that the measurement of CO2 values was uniformly too low by a small fraction p. Write a function that increases each value in co2_levels by the fraction p. (In other words if x is the value before the increase then x*(1+p) is the value after.) For this problem you need to use a ``range`, len() and indexing. Start by asking the user for the percentage. Output the first and last values of the revised list. Your program should end with the lines

    print('First: {:.2f}'.format(co2_levels[0]))
    print('Last: {:.2f}'.format(co2_levels[-1]))

    Here is an example of running your program:

    Enter the fraction: 0.03
    First: 329.63
    Last: 404.74
  5. Write a function called is_increasing that returns True if the values in the list it is passed are in increasing order and False otherwise. Use a for loop and indexing to accomplish this. Test the function with the following main code:

    print('co2_levels is increasing: {}'.format(is_increasing(co2_levels)))
    test_L1 = [ 15, 12, 19, 27, 45 ]
    print('test_L1 is increasing: {}'.format(is_increasing(test_L1)))
    test_L2 = [ 'arc', 'circle', 'diameter', 'radius', 'volume', 'area' ]
    print('test_L2 is increasing: {}'.format(is_increasing(test_L2)))
    test_L3 = [ 11, 21, 19, 27, 28, 23, 31, 45 ]
    print('test_L3 is increasing: {}'.format(is_increasing(test_L3)))

    These should be the only print() function calls in the code you submit.