I want to take a list, for instance List = [1,2,2]
, and generate its permutations. I can do this with:
NewList = [list(itertools.permutations(List))]
and the output is:
[[(1, 2, 2), (1, 2, 2), (2, 1, 2), (2, 2, 1), (2, 1, 2), (2, 2, 1)]]
The Problem: itertools.permutations
returns a list of length 1 whose only entry is the list of all permutations of List. That is:
NewList[0] == [(1,2,2),(1,2,2),(2,1,2),(2,2,1),(2,1,2),(2,2,1)]
and
NewList[1]
does not exist.
I want the output to be a list where each entry is one of the permutations. That is
NewList[0] == (1,2,2)
NewList[1] == (1,2,2)
NewList[2] == (2,1,2)
...
NewList[5] == (2,2,1)
The Question: Is there a command that will produce the permutations of List in this way? Failing that, is there a way to access the 'individual elements' of [list(itertools.permutations(List))]
so I can do things with them?
>>> from itertools import permutations
>>> list(permutations([1,2,2]))
[(1, 2, 2), (1, 2, 2), (2, 1, 2), (2, 2, 1), (2, 1, 2), (2, 2, 1)]
You don't need to put it in a list again. ie Don't do [list(permutations(...))]
(By doing []
you are making a nested list and hence are unable to access the elements using testList[index]
, though you could do testList[0][index]
but it would be better to just keep it as a list of tuples.)
>>> newList = list(permutations([1, 2, 2]))
>>> newList[0]
(1, 2, 2)
>>> newList[3]
(2, 2, 1)
Now you can access the elements by using their indices.
Why can't you do this:
NewList = [list(itertools.permutations(List))][0]
or even just this:
NewList = list(itertools.permutations(List))
By doing [ list(itertools.permutations(List)) ]
, you put the list of permutations (the one that you want) inside of another list. So the fix would be to remove the outer []
's
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