Introduction to Computer Programming

Lab 9: lists

Instructions

• Work on this lab with your partner (or on your own if you have not been assigned one).

• Unless otherwise indicated, use only the Python operations and commands we have described thus far in class.

• Show your work for a given problem to the instructor or one of the lab assistants before moving on to the next problem, but do not get too bogged down on any one problem.

• In the common case, you will not complete the exercises during our scheduled lab. It is then up to you to complete the lab on your own time.

• Rename your file to have both your names in it as: lab9_alpha_beta.py (if your names were Alpha and Beta).

• Email me a copy of your work (attach your version of the lab9 file - named as just indicated) by replying to the email that officially announces the lab. If working with a lab partner send me just one copy for the pair, but CC your partner.

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1. Try these in the IDLE shell, in order, one at a time:

    >>> a = []
    >>> type(a)
    >>> len(a)
    >>> a.append('Hello')
    >>> a.append(29)
    >>> a.append(False)
    >>> a
    >>> len(a)
    >>> a.append('whatever')
    >>> a
    >>> a.pop()
    >>> a
    >>> for x in a:
            print(x)
   
    >>> seasons = ['Winter', 'Spring', 'Summer', 'Fall']   # a list literal
    >>> seasons[3] = 'Autumn'   # lists are mutable
    >>> seasons
    >>> ','.join(seasons)
   
    >>> 'the quick brown fox'.split()
   
    >>> ns = [2, 11, 3, 7, 5]
    >>> ns[4]
    >>> max(ns)
    >>> sum(ns)
   
    >>> a = [99, 88]
    >>> b = a
    >>> b[0] += 1
    >>> b
    >>> a

2. Download and unzip the starter archive. Use IDLE to open lab9_examples.py in the lab9 folder. (Re)read the functions defined in that file and experiment with using them as in:

    >>> ns = [44, 66, 55, 99]
    >>> append_first(ns)
    >>> ns
    >>> decrement_list(ns)
    >>> ns
    >>> pop_first(ns)
    >>> ns
    >>> swap(ns, 0, 2)
    >>> ns
    >>> insert_at(ns, 1, 333)
    >>> ns
   
    >>> build_streak(5, 7)
   
    >>> xs = random_list(15)
    >>> xs
    >>> ys = xs[:]   # copying the list
    >>> xs[4] = -1
    >>> xs
    >>> ys
    >>> bubble_sort(xs)
    >>> xs
    >>> ys
    >>> selection_sort(ys)
    >>> ys

3. Experiment with using the mini_graphics module:

    >>> from mini_graphics import *
    >>> ROWS
    >>> COLUMNS
    >>> clear()
    >>> from random import randrange
    >>> for _ in range(200):
            paint(randrange(COLUMNS), randrange(ROWS))
            update()
    >>> clear()
    >>> for _ in range(200):
            paint(randrange(COLUMNS), randrange(ROWS))

4. Included in the lab9 folder is a runnable solution module called lab9x.py. You can use it to see the result of executing the solution version of any of the assigned exercises. After running either lab9_examples.py or your version of lab9 as a module in IDLE, you can import lab9x and access the solution versions in the IDLE shell as follows:

    >>> import lab9x
    >>> lab9x.build_zero_array(5)

If one of the exercises you are working on requires the solution to a previous exercise that you have not yet completed, you can use the solution version.

5. Rename your lab9.py as described above (following the aforementioned lab9_alpha_beta.py form). Use IDLE to open your renamed file in the lab9 folder. Remove the starter comment line in that file. Replace <YOUR NAME(s) GO HERE> with your name(s). Save as you go. Run the module in IDLE, test your functions in the IDLE shell.

Challenge problems available upon request.