python - Inserting a value into all possible locations in a list

Question

I am trying to do print all the possible outcomes of a given list and I was wondering how to put a value into various locations in the list. For example, if my list was [A, B], I want to insert X into all possible index of the list such that it would return this [X, A, B], [A, X, B], [A, B, X].

I was thinking about using range(len()) and a for loop but not sure how to start.

question from:https://stackoverflow.com/questions/2218238/inserting-a-value-into-all-possible-locations-in-a-list

Answer 1

You could do this with the following list comprehension:

[mylist[i:] + [newelement] + mylist[:i] for i in xrange(len(mylist),-1,-1)]

With your example:

>>> mylist=['A','B']
>>> newelement='X'
>>> [mylist[i:] + [newelement] + mylist[:i] for i in xrange(len(mylist),-1,-1)]
[['X', 'A', 'B'], ['B', 'X', 'A'], ['A', 'B', 'X']]