Dynamically creating an associative array of arrays

Question

I'm trying to dynamically create an associative array whose values are arrays. My current attempt is as follows but I'm not sure if it is correct or efficent.

foreach $line (@lines)                               # read line from a text dictionary 
{
    chomp( $line );
    my($word, $definition) = split(/\s/, $line, 2); # 
    $definition =~ s/^\s+|\s+$//g ;                 # trim leading and trailing whitespace

    if( exists $dict{$word} )
    {
        @array = $dict{$word};
        $len = scalar @array;
        $dict{$word}[$len] = $definition;
    }
    else
    {
        $dict{$word}[0] = $definition;
    }
}

Your entire if/else can be replaced by push @$dict{$word}, $definition. Right now you are copying the array just to compute its length. — Nemo
– Nemo, Commented Jul 18, 2013 at 1:41
that's because $dict{$word} doesn't have a value initially, so trying to cast that to an array doesn't work, because it's not an array reference. — xaxxon
– xaxxon, Commented Jul 18, 2013 at 2:43

xaxxon · Accepted Answer · 2013-07-18 06:13:48Z

2

pretty sure this works (can't test right now)

foreach $line (@lines)                               # read line from a text dictionary 
{
    chomp( $line );
    my($word, $definition) = split(/\s/, $line, 2); # 
    $definition =~ s/^\s+|\s+$//g ;                 # trim leading and trailing whitespace

    push @{$dict{$word}}, $definition;

}

(using unshift instead of push will put the new entry on the other side of the other entries)

edited Jul 18, 2013 at 6:13

answered Jul 18, 2013 at 2:38

xaxxon

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2 Comments

Slaven Rezic Over a year ago

Probably ||= [] may be omitted, thanks to autovivification.

xaxxon Over a year ago

Looks like you're right. Updating answer. I like the curlies around the cast, though, as it makes it very clear what's being done.

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