multiplying and combining all elements in a list by all others but without duplication/repetition

Question

we = [1,2,3,4]
for i in we:
    for e in we:
        print('('+str(i)+' - '+str(e)+')')
    #del we[0]

This is the result:

(1 - 1)
(1 - 2)
(1 - 3)
(1 - 4)
(2 - 1)
(2 - 2)
(2 - 3)
(2 - 4)
(3 - 1)
(3 - 2)
(3 - 3)
(3 - 4)
(4 - 1)
(4 - 2)
(4 - 3)
(4 - 4)

But I do not want the same elements to repeat like I have (1 - 3) so I do not want (3 - 1) to show and so on. I also need to use for loops in this

How about `itertools.combinations_with_replacement` or just `itertools.combinations`, depending on whether you want pairs like (1-1) or not? — kaya3, Dec 06 '19 at 02:16
`for c in itertools.combinations([1,2,3,4], 2): print(c)` # (1, 2) (1, 3) (1, 4) (2, 3) (2, 4) (3, 4) — Darkonaut, Dec 06 '19 at 02:17
@kaya3 Thanks I used itertools.combinations_with_replacement and I got it. thank you!! — Data_sniffer, Dec 06 '19 at 02:25

CypherX · Answer 1 · 2019-12-06T02:34:16.030

0

You can do this in a single line using list comprehension and itertools.combinations.

from itertools import combinations
['({} - {})'.format(e[0], e[1]) for e in list(combinations([1,2,3, 4], 2))]

Output:

['(1 - 2)', '(1 - 3)', '(1 - 4)', '(2 - 3)', '(2 - 4)', '(3 - 4)']

References:

edited Dec 06 '19 at 02:34

answered Dec 06 '19 at 02:27

CypherX

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I see that @Darknaut also suggested this method. So, voted up his comment. – CypherX Dec 06 '19 at 02:29

multiplying and combining all elements in a list by all others but without duplication/repetition

1 Answers1

References: