aartist has asked for the wisdom of the Perl Monks concerning the following question:

I have '|' seperated fields in the file and I like to sort on columns 1,2,4,6,9. How do I do this? I am looking for some better methods like sort_on_fields(1,2,4,6,9) rather than sort { $a[1] <=> $b[1] or .. }

Update: Just after finished writing the post, I found the wonderful 'File::Sort' module. That should do it. Thanks.

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Re: Sorting by Multiple Columns
by Corion (Patriarch) on Jun 09, 2011 at 20:12 UTC
Re: Sorting by Multiple Columns
by BrowserUk (Patriarch) on Jun 09, 2011 at 20:35 UTC
    I am looking for some better methods like sort_on_fields(1,2,4,6,9) rather than sort { $a1 <=> $b1 or .. }

    Assuming that you mean that the sort field numbers cannot be hard coded as in the FAQ, then something like this does the trick:

    #! perl -slw use strict; use Data::Dump qw[ pp ]; sub sortOnFields{ my $r; $r = $a->[ $_ ] <=> $b->[ $_ ] and return $r for @_; return 0; } my @data = map[ map int( rand 10 ), 1 .. 10 ], 1 .. 20; @data = sort{ sortOnFields( 0,2,4,6 ) } @data; pp \@data; __END__ C:\test>908993 [ [0, 9, 1, 9, 0, 8, 7, 5, 9, 5], [0, 2, 9, 7, 5, 9, 1, 8, 8, 7], [1, 0, 2, 4, 1, 8, 3, 4, 6, 4], [1, 6, 6, 7, 6, 0, 3, 1, 8, 8], [1, 8, 8, 0, 4, 5, 0, 8, 8, 3], [2, 5, 7, 6, 5, 4, 6, 8, 2, 0], [3, 2, 0, 4, 2, 5, 1, 1, 6, 6], [3, 2, 1, 2, 2, 4, 7, 9, 8, 5], [3, 1, 6, 9, 0, 3, 0, 5, 6, 4], [5, 5, 3, 8, 1, 1, 0, 5, 7, 0], [5, 1, 5, 7, 9, 8, 3, 3, 8, 7], [5, 6, 6, 4, 2, 9, 7, 7, 2, 4], [6, 9, 1, 6, 5, 5, 0, 4, 0, 1], [9, 3, 0, 3, 0, 1, 2, 2, 7, 0], [9, 2, 0, 6, 8, 6, 0, 6, 5, 0], [9, 7, 0, 3, 8, 2, 2, 3, 7, 0], [9, 1, 2, 7, 2, 9, 6, 7, 3, 9], [9, 5, 2, 0, 2, 4, 8, 0, 7, 1], [9, 9, 2, 2, 8, 5, 8, 3, 3, 0], [9, 1, 4, 4, 5, 0, 2, 6, 8, 8], ]

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