itertools.permutations

itertools.permutations(itr, r=None)

• The permutations function is used to:

  • Cycle through each element of an iterable
  • Return successive r length permutations of elements
• This iterable is based on the itr parameter
• The number of permutations is based on the r parameter
• The r parameter is optional and defaults to the length of the iterable
• permutations returns an iterator of successive r length permutations of elements in the iterable itr

Illustrating the permutations Function

>>> from itertools import permutations

>>> itr = permutations('ABC', 2)
>>> for i in itr: print(i)
('A', 'B')
('A', 'C')
('B', 'A')
('B', 'C')
('C', 'A')
('C', 'B')

>>> itr = permutations(range(3))
>>> for i in itr: print(i)
(0, 1, 2)
(0, 2, 1)
(1, 0, 2)
(1, 2, 0)
(2, 0, 1)
(2, 1, 0)

References

• Documentation of the Permutations Function from Itertools