Shivkumar - 1 year ago 55

Python Question

I have this list after permutation:

`import itertools`

print list(itertools.permutations([1,2,3,4], 2))

Here's the output :

[

In that list we can find replicated elements like (1,2) - (2,1) and (1,3) - (3,1) and so ..

What I want is to get only one replicate element from this list, output list like:

`[(1, 2),(1, 3),(1, 4),(2, 3),(2, 4),(3, 4)]`

Thanks in advance

Answer Source

You need the combinations of the list, and not the permutations. For that there is `itertools.combinations()`

function in Python:

```
>>> from itertools import combinations
>>> l = [1,2,3,4]
>>> list(combinations(l, 2))
[(1, 2), (1, 3), (1, 4), (2, 3), (2, 4), (3, 4)]
```

As per the document:

Permutationsare for lists(order matters)

Combinationsare for groups(order doesn’t matter).