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A little bench-marking can be helpful. For the case of converting an array to a hash where the array values become keys and the array index become values.

I've bench-marked the OP code as well as the variations presented in response, in addition I added my own solution to the problem (variation3). The clear winner is variation1.

my %hash; @hash{ @array } = 0 .. $#array;
#!/usr/bin/env perl use strict; use warnings; use Benchmark qw(:all); my @array=qw(a b c d e f g h); 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; } cmpthese(-10, { 'original' => sub{ original() }, 'variation1' => sub{ variation1() }, 'variation2' => sub{ variation2() }, 'variation3' => sub{ variation3() }, });
results:
Rate variation2 variation3 original variation1 variation2 142570/s -- -15% -35% -49% variation3 168018/s 18% -- -24% -40% original 220185/s 54% 31% -- -21% variation1 279147/s 96% 66% 27% --

In reply to Re: better array to hash conversion by ruzam
in thread better array to hash conversion by perltux

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