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Re: mem usage

by kejohm (Hermit)
on May 27, 2010 at 02:58 UTC ( #841867=note: print w/replies, xml ) Need Help??


in reply to mem usage

You could try using Tie::File with a Fisher-Yates shuffle in place:

#!perl use strict; use warnings; use Tie::File; my $filename = shift; die 'No file' unless $filename; my $tie = tie my @file, 'Tie::File', $filename, memory => 20_000_000; die "Couldn't tie $filename: $!" unless $tie; $tie->defer(); shuffle(\@file); $tie->flush(); undef $tie; untie @file; sub shuffle { my $deck = shift; # $deck is a reference to an array my $i = @$deck; while (--$i) { my $j = int rand ($i+1); @$deck[$i,$j] = @$deck[$j,$i]; } } __END__

This worked well enough for me using a simple text file containing 1 million lines of random numbers.

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