List Exercises

Table of Contents

Hand of Cards

Exercise 120 (Hand of Cards)

1. Make a list of cards like:
   cards = ["7H", "QC", "2S", "AD", "3C"]

2. Iterate over the list and print each card symbol with a space after it.
   Hint: To print without adding a newline use print(... end="")

OUTPUT

    Your hand: 7H QC 2S AD 3C

Make a table of contents

Exercise 121 (Make a table of contents)

1. Make a list of chapters like:

  chapters = [
    "The Setup",
    "A Good First Program",
    "Comments And Pound Characters",
    "Numbers And Math"
  ]

1. Use the enumerate() function to iterate over the list and print each chapter number and title.

OUTPUT

  Table of Contents

  Chapter 1: The Setup
  Chapter 2: A Good First Program
  Chapter 3: Comments And Pound Characters
  Chapter 4: Numbers And Math

Running Calculator

Exercise 122 (Running Calculator)

1. Make a list of numbers.

2. Iterate over the list. For each element:

• Add the element value to the running total.

• Print the value and the balance.

OUTPUT

            =  0
    + 8     =  8
    + 5     = 13

Reformat Contact from CSV

Exercise 123 (Reformat Contact from CSV)

1. Start with the string: "smith,john,415-555-5555"

2. Split it into a list on ,
   Hint: To split on a different delimiter use str.split(<delim>)

3. Print the full name capitalized, then the phone number.
   Hint: Access list elements with varname[<index-number>]

OUTPUT

    John Smith: 415-555-5555

Column lengths

Exercise 124 (Column lengths Exercise)

This exercise is to calculate the length of the longest value in each column.

Write a function that takes one argument table that should be a list of equally sized lists. Each child list is a “row”.

It should return a list the same size as the child rows, where each element is length of the longest value (once converted to a string) in all rows in the same position.

Example Usage

>>> max_lengths([["a", "bb", "ccc"]])
[1, 2, 3]
>>> max_lengths([[628, 4, 82], [140, 59, 23]])
[3, 2, 2]
>>> max_lengths([['lend', 'job', 'when'], ['mail', 'walk', 'prove']])
[4, 4, 5]

Solution template

def max_lengths(table):
    """Return a list of the longest length of columns
       (when converted to strings)

    Arguments:
      table (list): list of equal length lists

    >>> max_lengths([["a", "bb", "ccc"]])
    [1, 2, 3]
    >>> max_lengths([[628, 4, 82], [140, 59, 23]])
    [3, 2, 2]
    >>> max_lengths([['lend', 'job', 'when'], ['mail', 'walk', 'prove']])
    [4, 4, 5]
    """
    pass

Solution to Exercise 124 (Column lengths Exercise)

Listing 728 Column lengths Exercise

def max_lengths(table):
    """Return a list of the longest length of columns
       (when converted to strings)

    Arguments:
      table (list): list of equal length lists

    >>> max_lengths([["a", "bb", "ccc"]]) == [1, 2, 3]
    >>> max_lengths([[628, 4, 82], [140, 59, 23]]) == [3, 2, 2]
    >>> words = [['lend', 'job', 'when'], ['mail', 'walk', 'prove']]
    >>> max_lengths(words) == [4, 4, 5]
    """
    # in case of empty list, return an empty list
    if not table:
        return []

    # initialize lengths to all zeros, same size as the first row
    lengths = [0] * len(table[0])

    # iterate over each child list
    for row in table:

        # iterate over each value
        for i, value in enumerate(row):

            # handle weird values
            # None should be an empty string (not "None")
            # and convert everything else to a string
            if value is None:
                value = ""
            else:
                value = str(value)

            # the length of the value
            size = len(value)

            # if its longer than the current longest
            # then replace it
            if size > lengths[i]:
                lengths[i] = size

    # return the list of lengths
    return lengths

Columnize

Exercise 125 (Columnize)

This exercise is to format align a data into columns.

Write a function that takes one argument table that should be a list of equally sized lists. Each child list is a “row”. It should return a string where each line contains the text in one row, and the columns are aligned.

Note: This depends on the max_lengths() function from the Column lengths exercise.

Example Usage

>>> scores = [['Joe', 82], ['Billy', 59], ['Mary', 77]]
>>> text = columnize(scores)
>>> text
'Joe    82\nBilly  59\nMary   77'
>>> print(text)
Joe    82
Billy  59
Mary   77

Solution template

def columnize(table):
    """Return a string of aligned columns of text

    Arguments:
      table (list): list of equal length lists

    >>> columnize([['Joe', 82], ['Billy', 59], ['Mary', 77]])
    'Joe    82\\nBilly  59\\nMary   77'
    """
    # your code here

Solution to Exercise 125 (Columnize)

Listing 729 Columnize Exercise

from pythonclass.exercises.max_lengths import max_lengths

def columnize(table):
    """Return a string of aligned columns of text

    Arguments:
      table (list): list of equal length lists

    >>> columnize([['Joe', 82], ['Billy', 59], ['Mary', 77]])
    'Joe    82\\nBilly  59\\nMary   77'
    """

    # create empty lines list for formatted strings, and set seperator to be two spaces
    lines, sep = [], " " * 2

    # get the column widths
    sizes = max_lengths(table)

    for row in table:
        # an empty list for justified strings
        line = []

        for i, value in enumerate(row):
            # None should be an empty string (not "None")
            if value is None:
                value = ""

            # left justify value to this column size
            value = str(value).ljust(sizes[i])

            # add value line list
            line.append(value)

        # join justified strings with seperator
        text = sep.join(line)

        # add to lines list
        lines.append(text)

    # join lines with newline character and return
    return "\n".join(lines)