13.2. Tuple Packing

Wherever python expects a single value, if multiple expressions are provided, separated by commas, they are automatically packed into a tuple. For example, we can omit the parentheses when assigning a tuple of values to a single variable.

julia = ("Julia", "Roberts", 1967, "Duplicity", 2009, "Actress", "Atlanta, Georgia") # or equivalently julia = "Julia", "Roberts", 1967, "Duplicity", 2009, "Actress", "Atlanta, Georgia" print(julia[4])

Check your understanding

Which of the following statements will output Atlanta, Georgia

• print(julia['city'])
• julia is a tuple, not a dictionary; indexes must be integers.
• print(julia[-1])
• [-1] picks out the last item in the sequence.
• print(julia(-1))
• Index into tuples using square brackets. julia(-1) will try to treat julia as a function call, with -1 as the parameter value.
• print(julia(6))
• Index into tuples using square brackets. julia(-1) will try to treat julia as a function call, with -1 as the parameter value.
• print(julia[7])
• Indexing starts at 0. You want the seventh item, which is julia[6]

2. Create a tuple called practice that has four elements: ‘y’, ‘h’, ‘z’, and ‘x’.

==== from unittest.gui import TestCaseGui class myTests(TestCaseGui): def testOne(self): self.assertEqual(practice, ('y','h','z','x'), "Testing that pratice value is assigned to correct value.") myTests().main()

3. Create a tuple named tup1 that has three elements: ‘a’, ‘b’, and ‘c’.

==== from unittest.gui import TestCaseGui class myTests(TestCaseGui): def testOne(self): self.assertEqual(tup1, ('a', 'b', 'c'), "Testing that tup1 was created correctly.") myTests().main()

4. Provided is a list of tuples. Create another list called t_check that contains the third element of every tuple.

lst_tups = [('Articuno', 'Moltres', 'Zaptos'), ('Beedrill', 'Metapod', 'Charizard', 'Venasaur', 'Squirtle'), ('Oddish', 'Poliwag', 'Diglett', 'Bellsprout'), ('Ponyta', "Farfetch'd", "Tauros", 'Dragonite'), ('Hoothoot', 'Chikorita', 'Lanturn', 'Flaaffy', 'Unown', 'Teddiursa', 'Phanpy'), ('Loudred', 'Volbeat', 'Wailord', 'Seviper', 'Sealeo')] ==== from unittest.gui import TestCaseGui class myTests(TestCaseGui): def testOne(self): self.assertEqual(t_check, ['Zaptos', 'Charizard', 'Diglett', 'Tauros', 'Lanturn', 'Wailord'], "Testing that pratice value is assigned to correct value.") myTests().main()

5. Below, we have provided a list of tuples. Write a for loop that saves the second element of each tuple into a list called seconds.

tups = [('a', 'b', 'c'), (8, 7, 6, 5), ('blue', 'green', 'yellow', 'orange', 'red'), (5.6, 9.99, 2.5, 8.2), ('squirrel', 'chipmunk')] ==== from unittest.gui import TestCaseGui class myTests(TestCaseGui): def testOne(self): self.assertEqual(seconds, ['b', 7, 'green', 9.99, 'chipmunk'], "Testing that seconds was created correctly.") myTests().main()

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