#!/usr/local/bin/perl -w
use strict;
my  @data;
my $file='data_file';

open( DATA , $file);
@data=<DATA>; ### already read all of $file into @data
close(DATA);
print @data;

while (<$data>) { ### can make this 'for ( @data ) {'
my @fields = split ' ';
for my $row (0..$#fields) {
       push @{$data[$row]}, $fields[$row];
    }
}
use Data::Dumper;
print Dumper \@data;

[download]
Another solution would be to ditch the 
@data=<DATA>;

[download]
and change the while loop header to: 
while ( <DATA> ) {

[download]
The @data array in your version is taking the lines of the file in list context, so it takes all of them. The for loop can then just use the array. If you want to read just one line at a time into memory, you can use the while ( <DATA> ) { version.

While you're at it, you might want to look into lexical filehandles instead of barewords. Lexical filehandles really are the way to go.

Update: The for loop suggestion won't work because you'd be using the same array as what you're pushing into. I didn't notice they had the same name until I came back through the thread and saw ikegami's node. In order to use that, you'd have to change the name of one or the other.

In reply to Re^3: How to swap rows with columns? - Still unresolved :( by mr_mischief
in thread How to swap rows with columns? - Still unresolved :( by perl_geek

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