Package basics :: Module lists

Module lists

source code

Python uses square brackets to enclose lists.

>>> X = [24, 3.14, 'w', 7] #  List with 4 items
>>> Y = [100]    # list with one item
>>> Z = [] #empty list

Lists are sequences of items which may be of different data types.

>>> L = list('hi!')  # make a string a list
>>> L
['h', 'i', '!']
>>> M = list()
>>> M
[]

The following examples illustrate references to list elements or list subsequences:

>>> X[0]   # 1st element
24
>>> X[1]   # 2nd element
3.1400000000000001
>>> X[-1]   # last element
7
>>> X[0:2] # list of 1st and 2nd elements
[24, 3.1400000000000001]
>>> X[:-1] # list excluding last element

References to subsequences of a list are called slices. The following raises an IndexError

>>> X[4]   # Raises exception!
...
IndexError: list index out of range
>>> X + Y # Concatenation!
[24, 3.1400000000000001, 'w', 7, 100]

Lists allow value assignments, which change the value of a reference in place (in place assignment).

>>> X[2] = 5
>>> X
[24, 3.1400000000000001, 5, 7]
>>> X[0:2] = [1,3]
>>> X
[1, 3, 5, 7]

Only list-values can be assigned to slices.

Functions

[hide private]

demo_lists()

Function Details

[hide private]

demo_lists()

source code

None