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Generate All Permutation Of A List

09.20.2005
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        From Michael Davies's <a href=http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/252178>recipe</a>.

def all_perms(str):
    if len(str) <=1:
        yield str
    else:
        for perm in all_perms(str[1:]):
            for i in range(len(perm)+1):
                yield perm[:i] + str[0:1] + perm[i:]

Some example usage

>>> for p in all_perms(['a','b','c']):
	print p

['a', 'b', 'c']
['b', 'a', 'c']
['b', 'c', 'a']
['a', 'c', 'b']
['c', 'a', 'b']
['c', 'b', 'a']

A great use of generator and recursive call.

Comments

Snippets Manager replied on Mon, 2006/03/06 - 3:54am

Thanks, that's just what I was looking for
"Starting from scratch" is seductive but disease ridden
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