Column Sort on Array

drodinthe559 has asked for the wisdom of the Perl Monks concerning the following question:

Hello All - I'm trying to do a column sort on an array of an array based on the modification date. This is real frustrating getting this s to work. Basically I want sort on the date field so I can rename each file based on that. Any help will be greatly appreciated.

use strict;
use File::Find;
use File::stat;

my @results;

find(\&search, "c:/test");
sub search {
    if ($_ =~ m/ACH/ ) {
        push @ {$results[0]},  $_;
        push @ {$results[1]}, stat($_)->mtime;
    }
}

my @temp = reverse sort { $a->[0] cmp $a->[0]} @results;

foreach my $x (@temp){
    #print $results . "\n";
    print $x->[0] . "\t" . $x->[1] . "\n";
}
[download]

Comment on Column Sort on Array Download Code

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Re: Column Sort on Array by BrowserUk (Patriarch) on Jul 19, 2008 at 13:11 UTC
Picking out the sort from the tangle of unformatted code I see: `my @temp = reverse sort { $a->[0] cmp $a->[0]} @results;` [download] If you compare `$a->[0]` against `$a->[0]`, it will always be equal, so sort will do nothing. Is that the problem you are experiencing? Try replacing one of the `$a` with `$b` and see what difference it makes. Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. "Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."	[reply] [d/l] [select]
Re^2: Column Sort on Array by Anonymous Monk on Jul 19, 2008 at 13:16 UTC
I tried that with no luck. When I run it in Komodo, I notice that variable don't change no matter what I change in that line. I tried this. my @temp = reverse sort { $a->[0] cmp $b->[0]} @results;	[reply]
Re: Column Sort on Array by cdarke (Prior) on Jul 19, 2008 at 13:15 UTC
1. Try using code tags: `use strict; use warnings; use File::Find; use File::stat; my @results; find(\&search, "c:/test"); sub search { if ($_ =~ m/ACH/ ) { push @ {$results[0]}, $_; push @ {$results[1]}, stat($_)->mtime; } } my @temp = reverse sort { $a->[0] cmp $a->[0]} @results; foreach my $x (@temp){ #print $results . "\n"; print $x->[0] . "\t" . $x->1 . "\n"; }` [download] In the sort you are comparing $a->[0] with $a->[0], should probably be: `my @temp = reverse sort { $a->[0] cmp $b->[0]} @results;` [download] However I'm puzzled. You seem to be putting the mtime field into element 1, yet you are comparing element zero. Also, if you want to compare numbers then you should use <=> rather than cmp.	[reply] [d/l] [select]
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