Re: Array Shuffle

List::Util's shuffle is a little faster still. Adding:

my $sub3 = sub {
    shuffle (@randomarray);
};
[download]

and changing timethese to cmpthese (with other changes as required) gives:

           Rate  Sub 2  Sub 1 Sub 32
Sub 2   14869/s     --   -13%   -89%
Sub 1   17066/s    15%     --   -87%
Sub 32 131573/s   785%   671%     --
[download]

DWIM is Perl's answer to Gödel

Comment on Re: Array Shuffle Select or Download Code

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Re^2: Array Shuffle by ikegami (Patriarch) on Jun 11, 2007 at 14:43 UTC
Isn't List::Util's `shuffle` implemented in C/XS? I'd be more interested in seeing a comparion where both algorithms were implemented in C/XS (or where both algorithms were implemented in Perl).	[reply] [d/l]
Re^3: Array Shuffle by Limbic~Region (Chancellor) on Jun 11, 2007 at 16:43 UTC
ikegami, Well, yes. It falls back to a pure perl version if the XS version isn't available. This is unlikely to happen since List::Util is part of the core but there is nothing preventing you from using the pure perl version as part of the benchmark. Cheers - L~R	[reply]
Re^3: Array Shuffle by GrandFather (Saint) on Jun 11, 2007 at 19:11 UTC
I understand your intellectual curiosity wrt the algorithm, but my post was more a subtle hint that using a pre-packaged wheel is often a better way of spending time than polishing your own variant. Seems from OP's reply I picked the right answer. From the benchmark results I guessed XS was likely lurking in the background somewhere, but in this case that can be treated as a reasonable optimisation by the module author. There is no hint in the List::Util docs that indicate the implementation method, however the guts of the routine seems to be: `for (index = items ; index > 1 ; ) { int swap = (int)(Drand01() * (double)(index--)); SV *tmp = ST(swap); ST(swap) = ST(index); ST(index) = tmp; } XSRETURN(items);` [download] DWIM is Perl's answer to Gödel	[reply] [d/l]
Re^2: Array Shuffle by logie17 (Friar) on Jun 11, 2007 at 15:30 UTC
GrandFather, Thank you for the reference to List::Util. I was actually just seeking a way to improve my current algorithms. (To squeeze as much out of Perl as I possibly could for my own personal edification). I would curious ot know if List Util using C to gain the edge? Thanks again s;;5776?12321=10609$d=9409:12100$xx;;s;(\d*);push @_,$1;eg;map{print chr(sqrt($_))."\n"} @_;	[reply]