On Tue, Apr 12, 2005 at 08:41:15AM -0400, Bill Mill wrote: > On Apr 12, 2005 2:37 AM, Fredrik Lundh <[EMAIL PROTECTED]> wrote: > > "Bernard A." wrote: > > > > > i'm looking for a way to have all possible length fixed n-uples from a > > > list, i think generators can help, but was not able to do it myself, > > > maybe some one could point me out to an idea to do it ? > > > > did you try googling for "python permutations" ? > > > > here's the first hit: > > > > http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/190465 > > > > I've used that recipe a significant amount, and I feel like its > recursion really slows it down (but I haven't been profiled it). Does > anyone know of a non-recursive algorithm to do the same thing?
If you need the speed probstat.sf.net has permutations, combinations, and cartesian products written in C. I'm the author and I use pure-python versions when I know I'm just doing small lists (to avoid a dependency). >From your original problem it looks like you want a combination, not a permutation. Combinations don't care about order (just unique sets). >>> import probstat >>> for (item) in probstat.Combination([0,1,2,3,4], 3): ... print item ... [0, 1, 2] [0, 1, 3] [0, 1, 4] [0, 2, 3] [0, 2, 4] [0, 3, 4] [1, 2, 3] [1, 2, 4] [1, 3, 4] [2, 3, 4] -jackdied -- http://mail.python.org/mailman/listinfo/python-list
