in reply to Re^2: Hash of Arrays and File Operations
in thread Hash of Arrays and File Operations

@cols[1 .. $#cols] = map(tr /[1,2]/[0,1]/, @cols)

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I'm no tr expert, but isn't tr /[1,2]/[0,1]/ more simply written as tr/12/01/?

The following will replace all 1's with 0's, and all 2's with 1's, in all elements of the @cols array. It modifies the array in-place. 

map { tr/12/01/ } @cols;

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Update: I concur with AnonyMonk's hint that it is better written as: 

tr/12/01/ for @cols;

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Re^4: Hash of Arrays and File Operations
by Anonymous Monk on Jan 28, 2010 at 20:24 UTC
    tr/12/91/ for @cols[1.. $#cols];
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[d/l]

      I have tried the above syntax and it doesn't seem to be working.

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        You may think you have, but you made a mistake :) Show your code and I'll tell you where 
        #!/usr/bin/perl --

use strict;
use warnings;

use Data::Dumper;
my @cols = ( 12, 12, 12 );

print Dumper( \@cols ),"\n";

tr/12/91/ for @cols[1.. $#cols];

print Dumper( \@cols ),"\n";

__END__
$VAR1 = [
          12,
          12,
          12
        ];

$VAR1 = [
          12,
          '91',
          '91'
        ];

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[reply]
[d/l]

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