python list iteration

Question

I have a list iteration in python defined like this:

for i in range(5):
    for j in range(5):
        if i != j:
            print i , j

So for each element in my defined range [0..5] I want to get each element i, but also all other elements which are not i.

This code does exactly as I expect, but is there a cleaner way of doing this?

You could use range() only once before the two loops as a first level optimization — DhruvPathak
– DhruvPathak, Commented Mar 29, 2012 at 8:52
From an efficiency point of view, this is perfectly serviceable, unless you're calling it in a tight loop or significantly increasing 5, I wouldn't worry. From a legibility point of view, this is perfectly readable. — MattH
– MattH, Commented Mar 29, 2012 at 8:53

eumiro · Accepted Answer · 2012-03-29 08:50:42Z

10

Use itertools.permutations:

import itertools as it
for i, j in it.permutations(range(5), 2):
    print i, j

answered Mar 29, 2012 at 8:50

eumiro

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1 Comment

Beni Cherniavsky-Paskin Over a year ago

However, the OP's code is very easy to understand without requiring the reader to know itertools; itertools shines when you need to scale these to more dimensions or need it more than once.

Daemoneye · Accepted Answer · 2012-03-29 08:51:41Z

2

[(x,y)for x in range(5) for y in range(5) if x!=y]

answered Mar 29, 2012 at 8:51

Daemoneye

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1 Comment

Gray Over a year ago

Please provide more information in your answers. Some background or explanations for posterity is recommended.

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