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Re: help sorting hash of hashes by value

by johngg (Canon)
on Apr 08, 2022 at 15:40 UTC ( #11142839=note: print w/replies, xml ) Need Help??


in reply to help sorting hash of hashes by value

I first approached this by forming a "flattened" intermediate hash where the first and second level keys were joined with a NUL character. The keys of the new hash could then be sorted by the associated descending numeric values then used for the printf statement. This code

use strict; use warnings; my %hoh_test = ( foo1 => { bar => -0.12697, baz => -0.000398154, }, foo2 => { bar => -4.0183e-05, baz => 0, }, foo3 => { bar => 9.966003977e-06, baz => 0.0001939, }, ); my %flatter = map { my $k1 = $_; map { join( qq{\0}, $k1, $_ ), $hoh_test{ $k1 }->{ $_ } } keys %{ $hoh_test{ $k1 } }; } keys %hoh_test; my @sortedKeys = sort { $flatter{ $b } <=> $flatter{ $a } } keys %flatter; printf qq{foo: %s, ba: %s, value: %s\n}, split( m{\0}, $_ ), $flatter{ $_ } for @sortedKeys;

produces

foo: foo3, ba: baz, value: 0.0001939 foo: foo3, ba: bar, value: 9.966003977e-06 foo: foo2, ba: baz, value: 0 foo: foo2, ba: bar, value: -4.0183e-05 foo: foo1, ba: baz, value: -0.000398154 foo: foo1, ba: bar, value: -0.12697

This seemed a bit long-winded so I thought it might be possible to still use combined keys but mapping out array refs to perform an ST all in one fell swoop. This code

use strict; use warnings; my %hoh_test = ( foo1 => { bar => -0.12697, baz => -0.000398154, }, foo2 => { bar => -4.0183e-05, baz => 0, }, foo3 => { bar => 9.966003977e-06, baz => 0.0001939, }, ); printf qq{foo: %s, ba: %s, value: %s\n}, @{ $_ } for map { [ split( m{\0}, $_->[ 0 ] ), $_->[ 1 ] ] } sort { $b->[ 1 ] <=> $a->[ 1 ] } map { my $k1 = $_; map { [ join( qq{\0}, $k1, $_ ), $hoh_test{ $k1 }->{ $_ } ] } keys %{ $hoh_test{ $k1 } }; } keys %hoh_test;

produces identical output. I hope this is of interest.

Update: Corrected typo, s/tha/the/

Cheers,

JohnGG

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