Lukas Barth <m...@tinloaf.de>: > On Saturday, August 1, 2015 at 10:57:19 PM UTC+2, Marko Rauhamaa wrote: >> ======================================================================== >> def circularly_equal(l1, l2): >> length = len(l1) >> if length != len(l2): >> return False >> twice = l1 + l1 >> for i in range(length): >> if twice[i:i + length] == l2: >> return True >> return False >> ======================================================================== > > Nice idea! But I actually really need those "canonic rotations", since > I'm hashing them somewhere..
First, lists can't be used as dict keys, but that minor point is easy to overcome. Secondly, a hash doesn't need to be unique, it's enough for it to be discerning. So you could, for example, choose: sum([ hash(x) for x in L ]) + hash(sum(L)) That doesn't discern any permutations, but depending on your application might be good enough. That way, you use the "pretty good" hash function together with the circular equality test and you won't be needing any canonical representation for the key. Marko -- https://mail.python.org/mailman/listinfo/python-list
