9.2. Lists are mutable¶
The syntax for accessing the elements of a list is the same as for accessing the characters of a string: the bracket operator. The expression inside the brackets specifies the index. Remember that the indices start at 0:
>>> print(cheeses) Cheddar
Unlike strings, lists are mutable because you can change the order of items in a list or reassign an item in a list. When the bracket operator appears on the left side of an assignment, it identifies the element of the list that will be assigned.
The one-th element of
numbers, which used to be 123, is
You can think of a list as a relationship between indices and elements. This relationship is called a mapping; each index “maps to” one of the elements.
List indices work the same way as string indices:
Any integer expression can be used as an index.
If you try to read or write an element that does not exist, you get an
If an index has a negative value, it counts backward from the end of the list.
in operator also works on lists.