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.
On 23/05/2013 23:21, Dave Cragg wrote:
On 23 May 2013, at 21:11, Björnke von Gierke <b...@mac.com> wrote:
Yes, that is why I myself lean towards a feature request. For example the
following line could tell the engine to make a unique random number for each of
the supplied lines, to not have the problem with lines that come first getting
a higher probability:
sort theData by random(the number of lines in theData) of each
If we're going for a feature request, I'd suggest a new function "shuffle".
It's more descriptive than 'sort'. (We're trying to do the opposite of sorting.)
I'm also uncomfortable with using arbitrary high numbers. (How random should it
be?) When i've done this before, I've used the analogy of pulling names out of
a hat. So a custom function like this (for shuffling lines) rather than use
sort.
function shuffleLines pSource
put empty into tNew
put the number of lines of pSource into tNum
repeat with n = tNum down to 1
put random(n) into tRand
put line tRand of pSource & cr after tNew
delete line tRand of pSource
end repeat
return line 1 to -1 of tNew
end shuffleLines
Probably a little slow for large lists, but for things like shuffling answer
choices in a test, it's good enough.
Cheers
Dave
_______________________________________________
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
_______________________________________________
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
