Question

I need to make a permutation that looks like a sequence of 1-N with a 0 stuffed in place #k.

This method works, but is there anything simpler using builtin functions?

def permshift(n,k):
   return [0 if x == k else x+(x<k) for x in range(n)]

>>> permshift(7,0)
[0, 1, 2, 3, 4, 5, 6]
>>> permshift(7,1)
[1, 0, 2, 3, 4, 5, 6]
>>> permshift(7,2)
[1, 2, 0, 3, 4, 5, 6]
>>> permshift(7,3)
[1, 2, 3, 0, 4, 5, 6]
>>> permshift(7,4)
[1, 2, 3, 4, 0, 5, 6]
>>> permshift(7,5)
[1, 2, 3, 4, 5, 0, 6]
>>> permshift(7,6)
[1, 2, 3, 4, 5, 6, 0]

Answer 1

Just create a new list, and insert the 0 wherever you need to.

def permshift(n, k):
    lst = range(1, n)
    lst.insert(k, 0)
    return lst