Most pythonic way of rotating a circular list to a canonical point

Lukas Barth mail at tinloaf.de
Sun Aug 2 01:32:10 CEST 2015


On Sunday, August 2, 2015 at 1:05:32 AM UTC+2, Oscar Benjamin wrote:
> Do you really need the canonical rotation or just a hash that is invariant under rotations?

Having that canonical rotation would make the code simpler and faster, probably, but a rotationally invariant hash is a good start.

> I don't know of a solution to the former that is better than what you already have but the latter is an easier problem: Find the minimum element. Compute the hash of the rotated sequence for each occurrence of the least common element. Add those hashes together or multiply them or some similar operation. That's your hash that will compare equal for any rotation of a given sequence.

Yes, that sounds like an idea if I decide to just go with the hash. Thanks!

Lukas


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