Sorting hash of hash of hash by values

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

$VAR1 = {
    'host' => {
             'batch' => {
                    'run1' => {
                            'jobs' => {
                                 'Job name 1' => {
                                                 'duration' => '16',
                                                 'end' => '2011/07/01 
+23:50:36',
                                                 'start' => '2011/07/0
+1 23:50:19'
                                               },
                                 'Job name 2' => {
                                                  'duration' => '22',
                                                  'end' => '2011/07/02
+ 05:22:29',
                                                  'start' => '2011/07/
+02 05:22:06'
                                                },
                                    },
                            'duration' => '25'
                            'end' => '2011/07/02 05:22:29',
                            'start' => '2011/07/02 05:22:06'
                            },
                            
                    'run2' => {
                            'jobs' => {
                                 'Job name 1' => {
                                                 'duration' => '16',
                                                 'end' => '2011/07/01 
+23:50:36',
                                                 'start' => '2011/07/0
+1 23:50:19'
                                                },
                                 'Job name 2' => {
                                                  'duration' => '22',
                                                  'end' => '2011/07/02
+ 05:22:29',
                                                  'start' => '2011/07/
+02 05:22:06'
                                                },
                                    },
                            'duration' => '25'
                            'end' => '2011/07/02 05:22:29',
                            'start' => '2011/07/02 05:22:06'        
                               },
                       },
                 },
        };
[download]

Hash is layed out like this:

%Hash -> $host -> $batch -> $run -> 'jobs'      -> $jobname -> 'durati
+on'
                                 -> 'duration'             -> 'end'
                                 -> 'start'                 -> 'start'
                                 -> 'end'
[download]

Problem:
I would like to sort the hash by values such as:
- $Hash->{$cluster}->{$host}->{$batch}->{'start'}
- $Hash->{$cluster}->{$host}->{$batch}->{'jobs'}->{$jobname}->{'start'}
Therefore sorting by the 'start' values of the batch and jobs

foreach $host ( keys %hash )
{
    foreach $batch ( keys %{$hash{$host}} )
    {
        foreach $run ( keys %{$hash{$host}{$batch}} )
        {
            
            #print $hash{$host}{$batch}{$run}{'duration'}, "\n";
            print $hash{$host}{$batch}{$run}{'start'}, "\n";  #How do 
+I sort by this?
            #print $hash{$host}{$batch}{$run}{'end'}, "\n";
            
            foreach $job ( keys %{$hash{$host}{$batch}{$run}{'jobs'} )
            {
                print $hash{$host}{$batch}{$run}{'jobs'}{$job}{'start'
+}, "\n"; #How do I sort by this?
            }
        }
    }
}
[download]

I have tried using the sort { hash{cluster}{host}{batch}{$a}->{duration} <=> hash{cluster}{host}{batch}{$b}->{duration} } but it did not produce expected results. I also tried other variations I found online and searching through here.

Hoping someone could point me in the right direction, please!

Comment on Sorting hash of hash of hash by values Select or Download Code

Replies are listed 'Best First'.
Re: Sorting hash of hash of hash by values by jethro (Monsignor) on Jul 07, 2011 at 17:04 UTC
You don't seem to be far off, but I hope you didn't fall into the trap of trying to sort the hash itself. Hashes can't be sorted, but arrays or lists made from their keys. `foreach $batch ( keys %{$hash{$host}} ) { my @runs= keys %{$hash{$host}{$batch}; @runs= sort { $hash{$host}{$batch}{$a}{start} <=> $hash{$host}{$bat +ch}{$b}{start} } @runs; foreach $run (@runs) { ...` [download] Naturally you can compress this into one line and remove the need for @runs, but I wanted to show explicitly what I was doing Oh and it is untested. Wouldn't suprise me if I had made a silly mistake somewhere	[reply] [d/l]
Re^2: Sorting hash of hash of hash by values by legendx (Acolyte) on Jul 07, 2011 at 21:45 UTC
Hey thanks! that worked. I was able to sort by the $batch 'duration' values I was using `sort { $hash{$host}{$batch}{$run}{$a}{start} <=> $hash{$host}{$batch}{$run}{$b}{start} }` instead and it wasn't working. Why does `hash{$host}{$batch}{$a}{start} <=> $hash{$host}{$batch}{$b}{start}` work when I am not specifying the $run? Is it because Perl puts the two elements it wants to compare (which is the $run) into the special variables $a and $b?	[reply] [d/l] [select]
Re^3: Sorting hash of hash of hash by values by jethro (Monsignor) on Jul 08, 2011 at 08:56 UTC
Yes, $a and $b are aliases to values that get compared. Even if it were not it wouldn't make sense to add more dereferencing to a hash structure than there is depth. Just out of curiosity: Why did you write $a and $b into your code if you didn't know that?	[reply]
Re^4: Sorting hash of hash of hash by values by legendx (Acolyte) on Jul 08, 2011 at 14:47 UTC