How do you sort a hash of array refs?

el-moe has asked for the wisdom of the Perl Monks concerning the following question:

I have a hash of array refs

my %hash = ( TYPE => ["hole", "hole", "chain", "slot"],
             SIZE => [126, 93, 96, 130],
             STEP => ["pcb", "pcb", "array", "panel"],
             COMP => ["none", "none", "right", "left"], );
[download]

I need to sort the $hash{SIZE} array and have all the other arrays sort along with it.

I looked at a lot of documentation and found sorts of many types but none match my problem. I was thinking the Schwartzian Transform might work but I'm not sure how to get from the example to a working ST I can use...

Thanks in advance for all your help!!

Prost,
Moe

Comment on How do you sort a hash of array refs? Select or Download Code

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Re (tilly) 1: How do you sort a hash of array refs? by tilly (Archbishop) on Nov 16, 2000 at 05:09 UTC
Well normally for something like this I would arrange to have an array of hash refs: `my @array = ( {TYPE => "hole", SIZE => 126, STEP => "pcb", COMP => "none"}, {TYPE => "hole", SIZE => 93, STEP => "pcb", COMP => "none"}, {TYPE => "chain", SIZE => 96, STEP => "array", COMP => "right"}, {TYPE => "slot", SIZE => 130, STEP => "panel", COMP => "left"}, );` [download] and now sorting it is as easy as: `@sorted = sort {$a->{SIZE} <=> $b->{SIZE}} @array;` [download] This kind of design is better for a number of reasons. But still in your case you have an unfriendly data structure for the operation. Well here is a way to do this: `my @indices = sort {$hash{SIZE}[$a] <=> $hash{SIZE}[$b]} 0..$#{$hash{S +IZE}}; foreach my $key (keys %hash) { @{$hash{$key}} = @{$hash{$key}}[@indices]; # Slice }` [download] But honest, reversing the structure of your data structure now is advised if at all possible.	[reply] [d/l] [select]
Re: How do you sort a hash of array refs? by runrig (Abbot) on Nov 16, 2000 at 04:33 UTC
Try this: `my @sorted = sort { $hash{SIZE}[$a] <=> $hash{SIZE}[$b] } 0..$#{$hash{ +SIZE}}; $hash{$_} = [ @{$hash{$_}}[@sorted] ] for keys %hash;` [download]	[reply] [d/l]
Re: How do you sort a hash of array refs? by Dominus (Parson) on Nov 16, 2000 at 05:22 UTC
The original author may want to have a look at The indirect Sort. This is the technique that runrig demonstrated. The page linked above shows the same technique with a simpler example and a little more explanation.	[reply]
Re: Re: How do you sort a hash of array refs? by el-moe (Scribe) on Nov 16, 2000 at 05:32 UTC
Thanks runrig. I see what you're doing now. I tested it on my system and it's going to work.	[reply]


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