Nice one, Alex. I spent an hour convincing myself that the sA array could contain duplicate elements after the loop, until the penny dropped. Remind me never to play cards if you're shuffling. :-)
Dave On 24 May 2013, at 00:41, Alex Tweedly <a...@tweedly.net> wrote: > > Yes, that's a good shuffle for small data, but a bit slow for larger data > sets. I dug out an old function I wrote a few years ago (and converted it to > LC); this would be faster for large data sets (time taken grows linearly > rather than by the square of the number of lines). > > local sA, sIndex -- filled with random shuffle index, returned one-by-one > from fn calls > > function shuffleLines pSource > put empty into tNew > put the number of lines of pSource into tNum > -- fill an array with 'self' numbers > repeat with i = 1 to tNum > put i into tA[i] > end repeat > > repeat with n = tNum down to 1 > put random(n) into tRand > put tA[tRand] into sA[n] > put tA[n] into tA[tRand] > end repeat > put 0 into sIndex > sort lines of pSource by _shuffle() > return pSource > end shuffleLines > > function _shuffle > add 1 to sIndex > return sA[sIndex] > end _shuffle > > -- Alex. > _______________________________________________ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode
