Greetings Monks,
I'm trying to sort a reasonably large amount of data stored in a hash, and I've come up with code that works. However, I just don't like the code - it looks like I'd curse the programmer that wrote it (me) if I came across it.
I don't think there's anything wrong with my algorithm, but I'd greatly appreciate any comments on the style and maintainability of this code. More idiomatic ways to write it (in particular the two lines concerning $idx and splice) would also be welcomed.

What I'm doing should (hopefully) be fairly obvious from the code and comments, but here's a general description anyway.

  1. For each part number, sort so that the order numbers are in order, highest first
  2. For each part number, find (at most) the five highest order numbers
  3. Now display all the part numbers, ordering them by the order numbers
Note:
The data format isn't set in stone, and I'd be happy to change if a better alternative exists.

The code: 

#!/usr/bin/perl

use warnings;
use strict;

#example data below.
my %data = (
        #Partno    List of orders
        "A1111" => [qw/12345 1234 123456 2345 233 23456/],
        "B2222" => [qw/12345/],
        "C3333" => [qw/12345 6789/],
        "D4444" => [qw/12345 1234 6789/],
        "E5555" => [qw/12345 1234 6789 99999 999999 444444 22222 111/]
+,
        "F6666" => [qw/888888 9999999 6789/],
);


#Find the 5 numerically largest orders for each partno, and display th
+em.

foreach my $part_no (sort keys %data) {
        my @matching_orders;

        #Sort each order by number, largest first..
        @matching_orders = sort { $a <=> $b } @{$data{$part_no}};

        #We want upto the most recent five. Nasty hack.
        my $idx = $#matching_orders-4;
        $idx = 0 if($idx < 0);
        my @top_five = reverse splice @matching_orders, $idx;
        $data{$part_no} = \@top_five;
}

#I now know the first element of each part_no array is
#the largest order number that part_no appears on.
#sort by that element.

foreach my $part_no (sort { ${$data{$a}}[0] <=> ${$data{$b}}[0] } keys
+ %data) {
        #Now display them
        print "Part Number \"$part_no\" was found on: ";
        print join ", ", @{$data{$part_no}};
        print "\n";
}

[download]
Thanks in advance,
davis

In reply to Maintainability of hash-sorting code by davis

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