Perl: sort hash ref using multiple array ref values

Question

I have a hash ref with values being an array ref. I would like to sort the hash using multiple values. For example:

{ 'ID' => ['Age', 'Name', 'Start-Date'] }

I would like to sort by: 1) Age; then-by by 2) Start-Date (if Ages are equal). For example:

#!/usr/bin/env perl
use strict;
use warnings;

my $r = {
    'QX' => ['17','Jack','2022-05-31'],
    'ZE' => ['19','Jill','2022-05-31'],
    'RW' => ['17','Aida','2022-08-23'],
    'FX' => ['19','Bill','2022-05-23'],
    'IR' => ['16','Dave','2022-04-01']
};

for my $key (sort {$r->{$a}-[0] <=> $r->{$b}-[0] or $r->{$a}-[2] cmp $r->{$b}-[2]} keys %{$r}) {
    say STDERR "$key: $r->{$key}->[0] : $r->{$key}->[2] : $r->{$key}->[1]";
}

The code above, however, yields incosistent reults.

My expected output (sort by Age followed-by Start-Date) would be:

IR: 16 : 2022-04-01 : Dave
QX: 17 : 2022-05-31 : Jack
RW: 17 : 2022-08-23 : Aida
FX: 19 : 2022-05-23 : Bill
ZE: 19 : 2022-05-31 : Jill

What is `{$a}-[0]` (etc), with a hyphen ? Do you mean `{$a}->[0]` (with an arrow)? — zdim, Aug 16 '22 at 17:34
@h q: In what place you expect `RW: 17 : 2022-08-23 : Aida` to be printed? Since you mentioned first priority is for `Age` and second is for `Start-Date`. — vkk05, Aug 16 '22 at 17:40
Your code is all good, as are the results, once you replace (the typo?) hyphen by the correct arrow... The funny thing is that it runs, and produces results, even with that (non-sensical typo of) hyphen! — zdim, Aug 16 '22 at 17:42

score 2 · Accepted Answer · answered Aug 16 '22 at 17:52

2

$r->{$a}-[0]

should be

$r->{$a}->[0]

or just

$r->{$a}[0]   # Arrow optional between indexes.

You could also use

use Sort::Key::Multi qw( uskeysort );

uskeysort { $r->{ $_ }->@[ 0, 2 ] } keys %$r

answered Aug 16 '22 at 17:52

ikegami

367,544
15
269
518

Perl: sort hash ref using multiple array ref values

1 Answers1