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Python for Everyone: The PreTeXt Interactive Edition

Section 5.40 Functions with Tuples and Dictionaries Write Code Questions

Checkpoint 5.40.1.

Write a function called index_tup that takes in a tuple of strings, tup_strings, as a parameter and returns a string consisting of the characters at the zeroth index from the first string, the first index from the second string, the second index from the third string, etc. Add on to the string until the length of the current word is less than or equal to the current index. For example, index_tup(("peppermint", "athlete", "business", "everyone", "rhyme", "athlete")) should return ptsret.
Solution.
Write a function called index_tup that takes in a tuple of strings, tup_strings, as a parameter and returns a string consisting of the characters at the zeroth index from the first string, the first index from the second string, the second index from the third string, etc. Add on to the string until the length of the current word is less than or equal to the current index. For example, index_tup(("peppermint", "athlete", "business", "everyone", "rhyme", "athlete")) should return ptsret. 
def index_tup(tup):
    str1 = ''
    index = 0
    for word in tup:
        if len(word) > index:
            str1 += ((word[index]))
            index += 1
        else:
            return str1
    return str1

Checkpoint 5.40.2.

Write a function called list_tups_into_dict that takes in a list of tuples, list_of_tups as a parameter and returns a dictionary with the first index of the tuples as the keys and the second index of the tuples as the values. For example, list_tups_into_dict([('red', 3), ('blue', 2)]) should return {'red': 3, 'blue':2}.

Checkpoint 5.40.3.

Write a function squared_converter that takes in a list of numbers, num_list, and returns a dictionary with the numbers as keys and their squared value as values. For example, squared_converter([1,2]) should return {1: 1, 2: 4}.
Solution.
Write a function squared_converter that takes in a list of numbers, num_list, and returns a dictionary with the numbers as keys and their squared value as values. For example, squared_converter([1,2]) should return {1: 1, 2: 4}. 
def squared_converter(num_list):
    squared_dict = {}
    for num in num_list:
        squared_dict[num] = num * num

    return squared_dict

Checkpoint 5.40.4.

Write a function ordered_nums_tup() that takes a tuple, tup, that contains various items such as strings and numbers and returns a sorted list of the numeric values (type int and float) sorted in ascending order. For example, ordered_nums_tup(("hello", 5, 1)) should return [1, 5]. Hint: you can use isinstance(var, type) to check if a variable is of the given type.

Checkpoint 5.40.5.

Write a function triple_values that takes in a list of numbers, num_list, which adds every number in the list to a dictionary as the key and adds three times the number as the value. Then, change every even value (not the keys) in the dictionary to zero. For example, triple_values([1, 2]) should return {1: 3, 2: 0}.
Solution.
Write a function triple_values that takes in a list of numbers, num_list, which adds every number in the list to a dictionary as the key and adds three times the number as the value. Then, change every even value (not the keys) in the dictionary to zero. For example, triple_values([1, 2]) should return {1: 3, 2: 0}. 
def triple_values(num_list):
    triple_values_dict = {}

    for num in num_list:
        triple_values_dict[num] = num * 3

    for key, value in triple_values_dict.items():
        if (value % 2) == 0:
            triple_values_dict[key] = 0

    return triple_values_dict

====
from unittest.gui import TestCaseGui

class myTests(TestCaseGui):

    def testOne(self):
        self.assertEqual(triple_values([1, 2]), {1: 3, 2: 0}, "triple_values([1, 2])")
        self.assertEqual(triple_values([1,2,3.5,4.0,5,6]),{1: 3, 2: 0, 3.5: 10.5, 4.0: 0, 5: 15, 6: 0},"triple_values([1,2,3.5,4.0,5,6])")
        self.assertEqual(triple_values([0,2,15,-2,11,12]),{0: 0, 2: 0, 15: 45, -2: 0, 11: 33, 12: 0},"triple_values([0,2,15,-2,11,12])")


myTests().main()

Checkpoint 5.40.6.

Write a function count_chars that takes a string, str1, and returns a list of tuples ordered by the number of times each character appears in the string in descending order. For example, count_chars("babby") should return [('b': 3), ('a':1), ('y': 1)].
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