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Re: How to compare elements within an array

by Kenosis (Priest)
on Feb 20, 2014 at 19:03 UTC ( #1075626=note: print w/replies, xml ) Need Help??

in reply to How to compare elements within an array

One option is to use a hash to track the lab count (using the lab numbers as keys, so they can be numerically sorted later). If the count is 2, then the lab is paired, else it's unpaired:

use strict; use warnings; my %hash; while (<DATA>) { $hash{$1}++ if /^lab(\d+)_/; } for my $lab ( sort { $a <=> $b } keys %hash ) { print "lab$lab is ", ( $hash{$lab} == 2 ? 'paired' : 'unpaired' ), + "\n"; } __DATA__ lab1_set1.txt lab1_set2.txt lab2_set1.txt lab3_set1.txt lab3_set2.txt


lab1 is paired lab2 is unpaired lab3 is paired

Hope this helps!

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Re^2: How to compare elements within an array
by doubleqq (Acolyte) on Feb 20, 2014 at 20:11 UTC
    Thank you! This is such an elegant solution. You make hashes awesome. I did not realize you could use regex bare. I always believe you needed a {$variable =~} syntax.

      You're most welcome, doubleqq!

      I did not realize you could use regex bare.

      As I'm sure you've surmised, the regex implicitly operates on Perl's default scalar $_. As you examine more Perl code, you'll note regexes often being used in this context.

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