Tuples

What are tuples?

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- Tuples are another type of sequence in Python

- they are immutable

- they can be packed

- they can be unpacked to variables

- they can contain mutable objects

- lightweight compared to lists

Demo on how to use tuples	>>> t = 12345, 54321, 'hello!' >>> t[0] 12345 >>> t (12345, 54321, 'hello!') >>> # Tuples may be nested: ... u = t, (1, 2, 3, 4, 5) >>> u ((12345, 54321, 'hello!'), (1, 2, 3, 4, 5)) >>> # Tuples are immutable: ... t[0] = 88888 Traceback (most recent call last):   File "", line 1, in TypeError: 'tuple' object does not support item assignment >>> # but they can contain mutable objects: ... v = ([1, 2, 3], [3, 2, 1]) >>> v ([1, 2, 3], [3, 2, 1])
Ways on defining an empty tuple and a tuple with only 1 element	>>> empty = () >>> singleton = 'hello',    # <-- comma="" note="" p="" trailing=""> >>> len(empty) 0 >>> len(singleton) 1 >>> singleton ('hello',)
Packing and unpacking a tuple	>>> t = 23, 'grapes', 'linux'  # packing a tuple >>> t (23, 'grapes', 'linux') >>> >>> number, fruit, os = t  # unpacking a tuple >>> number 23 >>> fruit 'grapes' >>> os 'linux' >>> >>> number, fruit, os, car = t      # number of variables on the left side must match Traceback (most recent call last):  # the number of elements on the right tuple   File "", line 1, in ValueError: not enough values to unpack (expected 4, got 3) >>>
Tuples can be converted to list and vice-versa	>>> secret_message = "hello world" >>> list(secret_message) ['h', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd'] >>> tuple(secret_message) ('h', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd') >>> list(tuple(list(secret_message))) ['h', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd'] >>> ''.join(list(tuple(list(secret_message)))) 'hello world'
You can also do comparison between tuples	>>> t1 (1, 5, 7.6) >>> t2 (2, 8, 100) >>> >>> t1 < t2 True >>> >>> t1 > t2 False
You cannot delete a specific element in a tuple but you can delete all of them at once	>>> num = 600, 1, 5, 45.6 >>> num (600, 1, 5, 45.6) >>> del num[2] Traceback (most recent call last):   File "", line 1, in TypeError: 'tuple' object doesn't support item deletion >>> del num >>> num Traceback (most recent call last):   File "", line 1, in NameError: name 'num' is not defined >>>
Other operations that can be done on tuples	>>> len((1, 2, 3))  # length 3 >>> (1, 2, 3) + (4, 5, 6)  # addtion (concatenation) (1, 2, 3, 4, 5, 6) >>> ('Hi!',) * 4  # repetition ('Hi!', 'Hi!', 'Hi!', 'Hi!') >>> 3 in (1, 2, 3)  # membership True >>> for x in (1,2,3) : print (x, end = ' ')  # iteration ... 1 2 3 >>> >>>
Since tuples are also sequences, you can do slice and index operations against them	>>> T=('C++', 'Java', 'Python') >>> T[2] 'Python' >>> T[-2] 'Java' >>> T[1:] ('Java', 'Python') >>>
Other tuple functions	cmp(tuple1, tuple2) len(tuple) max(tuple) min(tuple) tuple(seq)