looping through hash of hashes reference perl - perl

Question

I have a hash of hashes that I am passing to a subroutine. In the subroutine I need to loop over the hash of hashes and access the value of the inner hash based on the outer hash's key. I am having trouble referencing and dereferencing the hash of hashes.
Here is my code.
use List::Util qw( min max );
##testingWords is array of strings
foreach(#testingWords)
{
#skip values that are '[' or ']' and move onto next value in array.
if($_ eq '[' or $_ eq ']')
{
next;
}
#if value in array matches key in %trainingHashRaw (hash of hashes)pass key to getMax.
if($trainingHashRaw{$_})
{
#key is $_, value is returned string from getMax
#%trainingHashRelative is hash of hashes
$testingHash{$_} = getMax($_, \%trainingHashRelative);
}
}
sub getMax
{
my $key = shift;
my $hash = shift;
my #max = ();
my $max = 0;
my $tag = "";
for my $i(keys $hash)
{
for my $j(keys $hash->{$i})
{
if($key eq $i)
{
push(#max, $hash->{$i}->{$j});
}
}
if(#max)
{
$max = max #max;
}
}
for my $i(keys $hash)
{
for my $j(keys $hash->{$i})
{
if($max == $hash->{$i}->{$j})
{
$tag = $j;
}
}
}
return $tag;
}

Answer 1

It is not very clear what your data structures should contain. So I made up an example for what I think that you have meant. The max value can occur more than once, so I keep track of all occurrences.
use strict;
use warnings;
use List::Util qw( min max );
use Data::Dumper;
# for each outer key we want to get the max of values of the associated hashref
# outer_a: 3
# outer_b: 100
my %hash_of_hashes = (
outer_a => {
inner_a_x => 1,
inner_a_y => 2,
inner_a_z => 3,
},
outer_b => {
inner_a_x => -100,
inner_a_y => 100,
},
outer_c => {
inner_a_x => 100,
inner_a_y => 1,
}
);
my ($max_value, $keys_of_max_value) = get_max( \%hash_of_hashes );
print "The max value $max_value occured in ", join( ' ,', #{$keys_of_max_value} ), ".\n";
sub get_max {
my ($hoh_ref) = #_; # reference to a hash of hashes
# %tmp keeps track of the outer_key for the max of the inner values
# %tmp = (
# 3 => ['outer_a'],
# 100 => ['outer_b', 'outer_c']
# )
my %tmp;
while ( my ($outer_key, $inner_hashref) = each %{$hoh_ref} ) {
my #inner_values = values %{$inner_hashref};
my $max_inner_values = max( #inner_values );
$tmp{$max_inner_values} ||= []; # for clarity create the arref expiclitly
push #{$tmp{$max_inner_values}}, $outer_key;
}
my $max_value = max( keys %tmp ); # 100
return ( $max_value, $tmp{$max_value} ); # 100, ['outer_a', 'outer_b']
}