sri1230 has asked for the wisdom of the Perl Monks concerning the following question:

Got a hash like this 

$hash = {
k1 => [a1, b1, c1, d1],
k2 => [a2, b2, c2, d1],
k3 => [a3, b3, c3, d3]
k4 => [a4, b4, c4, d3]
}
For the arrays where the d's are equal i want to do a numerical compar
+ision on the a's and add a priority number at the end

The output i expect
$hash = {
k1 => [a1, b1, c1, d1, 1],
k2 => [a2, b2, c2, d1, 2],
k3 => [a3, b3, c3, d3, 2]
k4 => [a4, b4, c4, d3, 1]
}

[download]

#basically for k1 and k2 the d's are equal and a1>a2 so i added 1 and 2 respectively at the end and a4>a3 etc. I have a solution but wanted to know if anyone had a easier solution for this.(like a one or 2 liner) Thanks in advance.

Replies are listed 'Best First'.
Re: Hash of Array Sort question
by ikegami (Patriarch) on Mar 18, 2010 at 15:27 UTC 
    use strict;
use warnings;

use Data::Dumper qw( Dumper );

my $hash = {
   k1 => [5, 'b1', 'c1', 1],
   k2 => [4, 'b2', 'c2', 1],
   k3 => [4, 'b3', 'c3', 3],
   k4 => [5, 'b4', 'c4', 3],
};

my $d_group;
my $a_group;
my $prio;
for my $rec (
    sort { $a->[3] <=> $b->[3] || $b->[0] <=> $a->[0] }
     values(%$hash)
) {
   if (!defined($d_group) || $rec->[3] != $d_group) {
      $d_group = $rec->[3];
      $a_group = $rec->[0];
      $prio = 1;
   }
   elsif ($rec->[0] != $a_group) {
      ++$prio;
   }

   $rec->[4] = $prio;
}

local $Data::Dumper::Sortkeys = 1;
print(Dumper($hash));

    [download]
    $VAR1 = {
          'k1' => [
                    5,
                    'b1',
                    'c1',
                    1,
                    1
                  ],
          'k2' => [
                    4,
                    'b2',
                    'c2',
                    1,
                    2
                  ],
          'k3' => [
                    4,
                    'b3',
                    'c3',
                    3,
                    2
                  ],
          'k4' => [
                    5,
                    'b4',
                    'c4',
                    3,
                    1
                  ]
        };

    [download]

    Update: Added test code. Tested. Fixed bug in sort expression.

[reply]
[d/l]
[select]
      There is one problem with that...the priority does not start from 1 for a different d_group
[reply]
        It does in your example, and that's the only place you mentioned what the values for priority should be. If it's not right, you'll need to explain what it should be.
[reply]
Re: Hash of Array Sort question
by Anonymous Monk on Mar 18, 2010 at 14:24 UTC
    I have a solution but wanted to know if anyone had a easier solution for this.(like a one or 2 liner) Thanks in advance.

    Show your solution

[reply]

      Here is what i am doing I am sorting and using the index instead of actually writing it as a value in array 

      my $hash;
foreach my $csn (keys %$datastore) {
  push @{$hash->{$datastore->{$csn}->[3]}}, $datastore->{$csn}->[0];
}

foreach  (keys %$hash) {
    my @sorted = sort { $a <=> $b } @{$hash->{$_}};
    $hash->{$_} = \@sorted;
}

foreach  (keys %$datastore) {
    $datastore->{$_} = [$datastore->{$_}->[1],$datastore->{$_}->[2],$d
+atastore->{$_}->[3], indexof($hash->{$datastore->{$_}->[3]}, $datasto
+re->{$_}->[0])];
}


sub indexof{
    my ($array_ref, $search_for)  = (shift, shift);
    my @array = @$array_ref;
    my( $index )= grep { $array[$_] eq $search_for } 0..$#array;
    return ($index + 1);
}

      [download]

      Created an other hash with each unique d as key and value is a array ref with sorted a's and then use the index

[reply]
[d/l]
        Sorting the elements of the array wasn't in your spec. Are you suppose to be doing that?
[reply]

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