Question

I work with multidimensional structures of arbitrary dimension. I have a Python list of xrange iterators, with each iterator representing an index of a multidimensional array:

indices = [ i, j, k ]

where

i = xrange(1,3)
j = xrange(3,5)
k = xrange(5,7)

To generate all the possible values, I use the following naive recursive code:

def travtree(index,depth):
    "Recursion through index list"
    if depth >= len(indices):
        # Stopping Condition
        print index
    else:
        # Recursion
        currindexrange = indices[depth]
        for currindex in xrange(len(currindexrange)):
            newindex = list(index) # list copy
            newindex.append(currindexrange[currindex])
            travtree(newindex,depth+1)

travtree([],0)

This works fine, but I was wondering, is there a more efficient, Pythonic way to do this? I tried looking in the itertools module but nothing jumps out at me.

Answer 1

>>> from itertools import product
>>> i = xrange(1,3)
>>> j = xrange(3,5)
>>> k = xrange(5,7)
>>> indices = [ i, j, k ]
>>> for item in product(*indices):
        print item


(1, 3, 5)
(1, 3, 6)
(1, 4, 5)
(1, 4, 6)
(2, 3, 5)
(2, 3, 6)
(2, 4, 5)
(2, 4, 6)