Lists

An ordered collection of items. The concept of lists is similar to the concept of arrays in other languages but with more extensive functionalities.

Defining a List

int_list = [10, 20, 30]

mixed_list = [10, "Hello", 20.30]

list_of_lists = [int_list, mixed_list, []]

Accessing a List

lst = [0, 1, 2, 3, 4]

one = lst[0]
one

0

four = lst[-1]
four

4

three = lst[-2]
three

3

Slicing a List

lst[0:-1]

[0, 1, 2, 3]

lst[:3]

[0, 1, 2]

lst[1:]

[1, 2, 3, 4]

lst[:] # Copy

[0, 1, 2, 3, 4]

lst[::2] # Every second element

[0, 2, 4]

lst[4:0:-1]

[4, 3, 2, 1]

Extending a List

lst + [5,6,7]

[1, 2, 3, 4, 5, 6, 7]

lst

[1, 2, 3, 4]

lst.extend([5,6,7])
lst

[1, 2, 3, 4, 5, 6, 7]

Unpack a List

lst = [1,2]
x, y = lst
print(x, " ", y)

1   2

_, y = lst
y

2