Hi Everyone, I'm parsing XML data using xml:libxml and am trying to determine the last category based on "category_id" and "parent_id" but can't figure out the logic to do it through hashes or arrays. The XML looks like this where the last category should be "Carrot"

Hi

So why should carrot be last?

No xml is required for that logic ;)

#!/usr/bin/perl --
use strict;
use warnings;
use Data::Dump qw/ dd /;

use constant +{ qw{ CAT_ID 0 NAME 1 PARENT_ID 2 } };

Main( @ARGV );
exit( 0 );

sub last_category(;+) {
    (
        sort {
            $a->[CAT_ID] 
            <=> 
            $b->[CAT_ID] 
        } @{ $_[0] }
    )[ -1 ]
}

sub Main {
    my @cats = (
      [443120, "Vegetables", 443026],
      [445720, "Carrot", 443120],
      [443026, "Food", undef ],
    );

    dd \@cats;
    dd( last_category( \@cats ) );
    @cats = sort { $a->[CAT_ID] <=> $b->[CAT_ID] } @cats;
    dd\@cats;
}
__END__
[
  [443120, "Vegetables", 443026],
  [445720, "Carrot", 443120],
  [443026, "Food", undef],
]
[445720, "Carrot", 443120]
[
  [443026, "Food", undef],
  [443120, "Vegetables", 443026],
  [445720, "Carrot", 443120],
]
[download]

Although once you know the goal ... xsh probably implements a max/min function

Yup https://xsh.sourceforge.io/doc2/html/index.html#max_function

$ xsh -q  xpath-max-min-11117492-correct.xsh
<category_id>443120 </category_id>
<category_id>445720 </category_id>
<category_id>443026 </category_id>
443120
445720
443026
max: 445720
min: 443026
[download]

$ cat xpath-max-min-11117492-correct.xsh
open "xpath-max-min-11117492.xml";
ls //category_id;
ls //category_id/node();
echo max: xsh:max( //category_id );
echo min: xsh:min( //category_id );
[download]