Re: sorting hash of array of hashes by value


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Re: sorting hash of array of hashes by value

by LanX (Saint)

on Aug 26, 2014 at 19:13 UTC ( [id://1098652]=note: print w/replies, xml )

Need Help??

in reply to sorting hash of array of hashes by value

Hashes can't be sorted b/c they have no order.

But you can keep sorted arrays of keys or values.

Your wish to keep the "path"s of a HoAoH sorted is a strong indication for me that you might wanna check the multi-dim hashes we inherited from Perl4.

Like this you could flatten your data to a 1-dim hash

$hash{$key0,$idx0,$key1}=<some floating point value>

and keep an array of sorted @keys .

Looks far simpler for me! (effectively it's using your concat approach w/o the overhead of the origanal HoAoH)

If you need this more often you might wanna check on tiehash solutions on CPAN to allow sorted hashes by encapsulating the sorted @keys .

HTH =)

Cheers Rolf

_{(addicted to the Perl Programming Language and ☆☆☆☆ :)}

edit

fixed syntax error by 's/;/,/'

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Re^2: sorting hash of array of hashes by value
by LanX (Saint) on Aug 26, 2014 at 21:25 UTC

AppleFritter

#!/usr/bin/perl

use strict;
use warnings;
use feature qw/say/;
use Data::Dump qw/pp dd/;


my %data = (
    "key0.1" => [
        {
            "key1.1" => 3.3,
            "key1.2" => 17.8,
            "key1.3" => -2.4,
        },
        {
            "key1.4" => 5.1,
            "key1.5" => 13,
        },
        {
            "key1.6" => -69,
            "key1.7" => 127,
            "key1.8" => 2.718,
            "key1.9" => 3.3,
        },
    ],
    "key0.2" => [
        {
            "key1.10" => 3.3,
            "key1.11" => 2.5,
        },
        {
            "key1.12" => -33,
        },
    ],
);

my %flat = ();

while (my ($k0,$v0) = each %data) {
    my $k1=-1;
    for my $v1 (@$v0) {
        $k1++;
        while (my ($k2,$v2) = each %$v1) {
            $flat{$k0,$k1,$k2} = $v2;
        }
    }
}

my @sorted_keys = sort { $flat{$a} <=> $flat{$b} } keys %flat;

for my $k (@sorted_keys) {
    my $v = $flat{$k};
    say "$v \t<= \t", join ",  ", split ( $; , $k );
}
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Output: