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

How can I create a hash with 2 key value pairs that also links to an array of data? I am not sure if this is caleld a multidimensional hash of arrays.

Upon reading a file I need to compare 2 vaules for example Network and connection type.

If these values do not exist create the new values and store the trailing data with them.

I currently have the following which works with only one key pair, but it is over writing the previous data because I am only comparing one field: 

@str = qw( 7 house network_name 4 6); 

if($myhash {$str[2]}}){ #if found
   // if netowrk_name is found increment the values of [3] and [4]

}
else{
   //must be new so ad new data to hash    
}

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But I need to compare and store 2 results.
example

I need to store and compare [0] and [2] and then have that array of data behind it.

Can someone shed some light on this for me?

thanks,
Kev

Edit by tye

Replies are listed 'Best First'.
Re: multidimensional hash of array
by Masem (Monsignor) on May 31, 2001 at 19:12 UTC
    There's two ways that you can do this in perl:

    One, create a hash of hashs of arrays: 

    my %hash = ( network_type_1 => { conn_type_1 => [ 1 ],
                                 conn_type_2 => [ 2 ] },
             network_type_2 => { conn_type_1 => [ 3 ],
                                 conn_type_2 => [ 4 ] } );
# To get at the elements:
print $hash{ $network }->{ $connection }->[ $pos ];

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    Alternatively, if there is a way to delimit the network and connection type into one string, you can get away with just a hash of arrays: 
    my %hash = ( 'network-type_1|conn_type_1' => [ 1 ],
             'network-type_1|conn_type_2' => [ 2 ],
             'network-type_2|conn_type_1' => [ 3 ],
             'network-type_2|conn_type_2' => [ 4 ] ); 
print $hash{ "$network|$conn" }->[ $pos ];

    [download]
    While the latter is probably easier to type out, the former case is easier to understand.

    Dr. Michael K. Neylon - mneylon-pm@masemware.com || "You've left the lens cap of your mind on again, Pinky" - The Brain
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Re: multidimensional hash of array
by bikeNomad (Priest) on May 31, 2001 at 19:17 UTC
    Hi Kev,
    You can make an anonymous array reference using square brackets: 
    my %myhash;
my @str = qw( 7 house network_name 4 6);
my $netName = $str[2];
if (defined($myhash{$netName})) { #if found
 my $arrayRef = $myhash{$netName};
 $arrayRef->[0]++; # increment numbers
 $arrayRef->[1]++;
} else {
 # must be new so ad new data to hash
 $myhash{ $netName } = [ @str[3..4] ]
}

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