Python: Essential Reference, Third Edition

Operations on Sequences

The following operators can be applied to sequence types, including strings, lists, and tuples:

Operation	Description
s + r	Concatenation
s * n, n * s	Makes n copies of s, where n is an integer
s % d	String formatting (strings only)
s[i]	Indexing
s[i:j]	Slicing
s[i:j:stride]	Extended slicing
x in s, x not in s	Membership
for x in s:	Iteration
len(s)	Length
min(s)	Minimum item
max(s)	Maximum item

The + operator concatenates two sequences of the same type. The s * n operator makes n copies of a sequence. However, these are shallow copies that replicate elements by reference only. For example, consider the following code:

 a = [3,4,5] # A list b = [a] # A list containing a c = 4*b # Make four copies of b # Now modify a a[0] = -7 # Look at c print ...