Iterating over every two elements in a list in Python [duplicate]

Question

How do I iterate over all pair combination in a list, like:

list = [1,2,3,4]

Output:

1,2
1,3
1,4
2,3
2,4
3,4

Thanks!

falsetru · Accepted Answer · 2014-11-19 13:00:29Z

4

>>> import itertools
>>> lst = [1,2,3,4]
>>> for x in itertools.combinations(lst, 2):
...     print(x)
...
(1, 2)
(1, 3)
(1, 4)
(2, 3)
(2, 4)
(3, 4)

BTW, don't use list as a variable name. It shadows the builtin function/type list.

answered Nov 19, 2014 at 13:00

falsetru

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Comments

Vishnu Upadhyay · Accepted Answer · 2014-11-19 13:00:53Z

1

Use itertools.combinations

>>> import itertools
>>> list(itertools.combinations([1,2,3,4], 2))
[(1, 2), (1, 3), (1, 4), (2, 3), (2, 4), (3, 4)]

answered Nov 19, 2014 at 13:00

Vishnu Upadhyay

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stang · Accepted Answer · 2014-11-19 13:01:22Z

-2

You can use a nested for loop as follows:

list = [1,2,3,4]
for x in list :

    for y in list :

        print x, y

answered Nov 19, 2014 at 13:01

stang

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This will produce the Cartesian product instead (e.g. you'll get (1,1) and (3,1) and (4,4)).