Combinatorial of elements in Python?

[Mikael Olofsson]

Sebastian Bassi wrote:
> Hello, could you do it for an indefinite number of elements? You did
> it for a fixed (2) number of elements. I wonder if this could be done
> for all members in a dictionary.

What is unclear here is in what order the keys should be visited. The 
following assumes that the keys should be considered in alphanumeric order.

 >>> def combine(d):
    if not d:
        return []
    elif len(d)==1:
        return d.values()[0]
    else:
        keys = d.keys()
        keys.sort()
        leftKeys = keys[0:len(keys)//2]
        rightKeys = keys[len(keys)//2:]
        leftDict = dict((key,d[key]) for key in leftKeys)
        rightDict = dict((key,d[key]) for key in rightKeys)
        return [x+y for x in combine(leftDict) for y in combine(rightDict)]

   
 >>> 
A={'field1':['a','A'],'field2':['b','B'],'field3':['c','C'],'field4':['d','D']}
 >>> combine(A)
['abcd', 'abcD', 'abCd', 'abCD', 'aBcd', 'aBcD', 'aBCd', 'aBCD', 'Abcd', 
'AbcD', 'AbCd', 'AbCD', 'ABcd', 'ABcD', 'ABCd', 'ABCD']


HTH again
/MiO