functional programming: sort to shuffle

It shuffles the parameters list:

sub shuffle { map { @_=sort { int (3*rand)-1 } @_ } 0..5 }
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Note that I go thru 6 iterations to get "sufficient" disorder.

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Re: sort to shuffle by demerphq (Chancellor) on Sep 03, 2001 at 15:06 UTC
Cool idea. stefp++. Curious if sort could get into a 'never finish' scenario if the right values came up from rand though? Thought you might like this version of the fisher yates shuffle. `sub fy_shuf{my($l,$c,$r)=@_;map{$r=int(rand($_+1)); @$l[$_,$r]=@$l[$r,$_]}reverse 0..$#$l for 0..$c\|\|0}; my @a=(1..52); fy_shuf(\@a,5);` [download] UPDATE Having had a look at japhy home node I borrowed an idea from him and reduced it more. (Oh and I decided that shuffling mutiple times was unecessary.) `sub fy_shuf{my($l,$r)=@_;map{$r=int(rand(@$l-$_+1));@$l[-$_,$r]=@$l[$r +,-$_]}0..$#$l};` [download] Yves -- You are not ready to use symrefs unless you already know why they are bad. -- tadmc (CLPM)	[reply] [d/l] [select]
Re: Re: sort to shuffle by stefp (Vicar) on Sep 03, 2001 at 18:30 UTC
It really depends on the internal sort algorithm. The "never finish" scenario is not the worse possible one: on some old versions of perl, my shuffle function crashes the perl interpretor :) That is why this really belongs to the obfuscation category... to answer a remark on the CB. Anyway, on 5.6, it works fine and dandy. -- stefp	[reply]


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