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in reply to Re: better array to hash conversion
in thread better array to hash conversion

As the array size grows, it doesn't take long for the OPs original to out pace variation1. It only requires a 200,000 or so for that to happen, and the benefits mount geometrically as the array size grows:

#!/usr/bin/env perl use strict; use warnings; use Benchmark qw(:all); our @array = 'aaaa' .. 'lzzz'; print "$#array\n"; sub original { my %hash; for (my $idx=0; $idx<@array; $idx++) { $hash{$array[$idx]} = $idx;} } sub variation1 { my %hash; @hash{ @array } = 0 .. $#array; } sub variation2 { my %hash = map { $array[$_] => $_ } 0..$#array; } sub variation3 { my $idx = 0; my %hash = map { $_ => $idx++ } @array; } sub variation4 { my $idx = 0; my %hash; $hash{ $_ } = $idx++ for @array; } cmpthese -5, { 'original' => \&original, 'variation1' => \&variation1, 'variation2' => \&variation2, 'variation3' => \&variation3, 'variation4' => \&variation4, }; __END__ C:\test>junk91 210911 Rate variation2 variation3 variation1 original variatio +n4 variation2 2.08/s -- -2% -36% -38% -4 +2% variation3 2.12/s 2% -- -35% -37% -4 +1% variation1 3.26/s 57% 54% -- -3% - +9% original 3.37/s 62% 59% 3% -- - +6% variation4 3.57/s 72% 68% 9% 6% +--

(I've added another variation that works better for large arrays.)


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