2.1.5 Sequence Types

There are three sequence types: strings, lists and tuples.

Strings literals are written in single or double quotes: 'xyzzy', "frobozz". See Chapter 2 of the Python Reference Manual for more about string literals. Lists are constructed with square brackets, separating items with commas: [a, b, c]. Tuples are constructed by the comma operator (not within square brackets), with or without enclosing parentheses, but an empty tuple must have the enclosing parentheses, e.g., a, b, c or (). A single item tuple must have a trailing comma, e.g., (d,).     

Sequence types support the following operations. The "in" and "not in" operations have the same priorities as the comparison operations. The "+" and "*" operations have the same priority as the corresponding numeric operations.^2.3

This table lists the sequence operations sorted in ascending priority (operations in the same box have the same priority). In the table, s and t are sequences of the same type; n, i and j are integers:

Operation	Result	Notes
x in s	1 if an item of s is equal to x, else 0
x not in s	0 if an item of s is equal to x, else 1
s + t	the concatenation of s and t
s * n, n * s	n copies of s concatenated	(3)
s[i]	i'th item of s, origin 0	(1)
s[i:j]	slice of s from i to j	(1), (2)
len(s)	length of s
min(s)	smallest item of s
max(s)	largest item of s

          

Notes:

(1)

If i or j is negative, the index is relative to the end of the string, i.e., len(s) + i or len(s) + j is substituted. But note that -0 is still 0.

(2)

The slice of s from i to j is defined as the sequence of items with index k such that i <= k < j. If i or j is greater than len(s), use len(s). If i is omitted, use 0. If j is omitted, use len(s). If i is greater than or equal to j, the slice is empty.

(3)

Values of n less than 0 are treated as 0 (which yields an empty sequence of the same type as s).