Python itertools module

http://docs.python.org/library/itertools.html

 

This module implements a number of iterator building blocks inspired by constructs from APL, Haskell, and SML. Each has been recast in a form suitable for Python.

 

The module standardizes a core set of fast, memory efficient tools that are useful by themselves or in combination. Together, they form an “iterator algebra” making it possible to construct specialized tools succinctly and efficiently in pure Python.

 

 

>>> import itertools
>>> for x in itertools.repeat(10,3): print x

 
10
10
10

 

>>> for x in itertools.islice(itertools.count(0),5):print x

0
1
2
3
4