Perl Hash table more than 2 dimensions - perl

Question

I'm trying to create an hash table with 6 dimensions : an hash table of an hash table of an hash table.. etc
I get my data from a file in local (by using REGEX and split function). The data I get are like :
northPartner1;southServiceCall1;northService1;nbNorthCall1;nbSouthCall1
I would like to store the data in many hash tables to use them to create an HTML array.I'm not very comfortable with hash table it's a new concept for me.
The problem is I didn't achieve to create an hash table with many dimensions.
I succeeded to do something like that:
#get the data
my $serviceN;
my $serviceS;
my $partnerN;
my $nbCallN;
my %northServices= () ;
my %northCall= ();
open (TraficFile, "$date/volumetries.csv") || die "Can't open: $!";
while(defined($_=<TraficFile>)) {
my #champsOutput = split(/\;/);
#get services.
if ($champsOutput[4]=~/Service Call/i){next;}
if ($champsOutput[4]=~/.*#/) {
($serviceS, $serviceN) = split(/#/,$champsOutput[4]);
$partnerN = $champsOutput[0];
}#endif
$nbCallN = $champsOutput[5];
print "nb : $nbCallN \n";
$northServices{$serviceN}{$partnerN}++;
}#while
#Print result
foreach $serviceN (keys %northServices){
print ('***'," $serviceN ",'***',"\n");
foreach my $partnerN ( keys %{ $northServices{$serviceN} } ){
print " $partnerN \n";
}
}
I have for each North Service the name of the North Partners,
but I would like to add hash tables like that :
$northServices={
'nameNorthService1' => {
'nameNorthPartner1' => 'numberOfNorthCall' => 'nameSouthService1' => 'numberOfCall',
=> 'nameSouthService2' => 'numberOfCall',
=> 'nameSouthService3' => 'numberOfCall',
'nameNorthPartner2' => 'numberOfNorthCall' => 'nameSouthService1' => 'numberOfCall',
=> 'nameSouthService2' => 'numberOfCall',
}
'nameNorthService2' => {
'nameNorthPartner1' => 'numberOfNorthCall' => 'nameSouthService1' => 'numberOfCall',
}
...
}
The numberOfNorthCall is divided in many South services which have each an numberOfCall.
I really don't know how to create others hash tables to encapsulate all this data like the model above.
I tried to create an other hash table in the while(), for example :
$northCall{$nbCallN} = $nbCallN;
$serviceNord{$serviceN}{$partnerN}{$northCall{$nbCallN}}++;
I tried to create references too :
my $rec = {};
$serviceNord{$serviceN}{$partnerN} = $rec;
$rec->{$nbCallN}++;
It seem to be the wrong way, but I didn't find anything to help me to create hash table with more than two dimensions.
If you know a way, do not hesitate.

Answer 1

First off - I'm going to suggest you're trying to do something entirely too complicated. Whilst you can do a hash of hashes of hashes etc. this is going to be quite painful.
However the root of your problem I think will be because you're misunderstanding the difference between: -> and =>. The former dereferences a hash. The latter is functionally equivalent to a comma.
But pretty fundamentally - you don't have multidimensional hashes - you have a top level hash of hash references.
If you do:
use strict;
use warnings;
my %hash;
$hash{firstlayer}{secondlayer}++;
print $hash{firstlayer};
You'll get a hash reference.
However, I think what you might want to consider is stopping using complex nested hashes, and instead try and put together an object. (Don't get put off - objects are basically 'complex data structures' that might include some code).
To create a nested hash declaratively:
use strict;
use warnings;
use Data::Dumper;
my $value = "value";
my $services = {
key1 => $value,
key2 => {
subkey => $value,
subkey2 => $value,
},
key3 => {
subkey1 => {
subsubkey1 => $value,
subsubkey2 => $value,
},
},
};
print Dumper \$services;
You can also add/access via:
print $services->{key3}->{subkey1}->{subsubkey2};
If you had created it with a %sigil, e.g.
my %services = (
#NOTE - different bracket too!
then that'd be
print $services{key3}{subkey1}{subsubkey2};
They're functionally similar - the key difference is that '->' tells perl that this is a reference to follow. Which style you use is more a matter of what makes more sense in your code.
But I would still suggest consider doing it OO style, and create an object with properties. (Objects are basically hashes, but let you do some more interesting things)
#MyService.pm
use strict;
use warnings;
package MyService;
sub new {
my ( $class ) = #_;
my $self = {};
bless ( $self, $class );
return $self;
}
sub set_name {
my ( $self, $name ) = #_;
$self -> {name} = $name;
}
sub add_partner {
my ( $self, $partner ) = #_;
push ( #{ $self -> {partners} }, $partner );
}
sub get_partners {
my ( $self ) = #_;
return #{ $self -> {partners} };
}
And then you can:
use strict;
use warnings;
use MyService;
my #services;
my $service = MyService -> new();
push ( #services, $service );
$service -> set_name ( 'nameNorthService1' );