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As long as we're (micro)optimizing, why even take references to the elements of @_ at all? Just shuffle indices of @_ and grab things out of @_ as they are needed. I guess indexing an array is a tiny bit faster than following a scalar ref.
sub blokhead (@) { my @a = (0 .. $#_); my $i = @_; my $n; map+( $n=rand($i--), $_[$a[$n]], $a[$n]=$a[$i] )[ 1 ], @_; }
It's clearly not a significant improvement, but does seem to be consistently a tiny bit faster...

On large data:

our @data = map { 'x' x 1000 } 1..1000; cmpthese -2, { map { $_ => "$_ \@data" } qw/naive listutil buk ikegami + blokhead/ }; Rate naive ikegami listutil buk blokhead naive 76.1/s -- -26% -47% -88% -88% ikegami 103/s 36% -- -28% -84% -84% listutil 143/s 89% 39% -- -78% -78% buk 638/s 739% 518% 345% -- -1% blokhead 643/s 745% 522% 348% 1% --
On small data:
our @data = ("xxx") x 1000; cmpthese -2, { map { $_ => "$_ \@data" } qw/naive listutil buk ikegami + blokhead/ }; Rate naive listutil ikegami buk blokhead naive 328/s -- -26% -44% -49% -49% listutil 445/s 36% -- -24% -30% -31% ikegami 589/s 80% 32% -- -8% -9% buk 637/s 94% 43% 8% -- -1% blokhead 646/s 97% 45% 10% 1% --

blokhead


In reply to Re^2: About List::Util's pure Perl shuffle() by blokhead
in thread About List::Util's pure Perl shuffle() by blazar

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