Hash of arrays

eg:

Query=  378.txt WGF.0.8  gi|15228342
GO:0004023  GO:0005507   GO:0006445

In fact, 1 "gi" corresponds 1 or 1 or multiple "go". so you can use a hash of arrays when you want to look up each array (a bunch of "go" record) by the particular string (gi record) rather than merely by an index number. eg:

%hash = (
        "gi|15228342" => [ "GO:0004023", "GO:0005507", "GO:0006445"],
);

to access and print a hash of arrays. just follow this code below:

foreach $gi( keys %hash ) {
        print "$gi\n @{ $hash{$gi} }\n";
}

also see: Programming perl, chapter 9.2. Hashes of Arrays