Re: your code--I think that were I presented with the same problem I'd probably do it like this:

    my %author;
    while (<FH>) {
        next unless /^\d{6}=[^|]+\|/;
        my($l, $r)  = split /=/, $_, 2;
        $author{$l} = [ split /\|/, $r, 2 ];
    }
[download]

I don't like temporary variables much, either, but this, to me, seems:

• more readable
• more efficient, both in terms of memory and "algorithm". Your code loops over the data three times (I think); the above would loop over it only once. Furthermore, your code loads the entire contents of FH into memory at the same time, while the above processes the file line by line.

I'm not trying to bash you or anything. :) Readability is often a rather subjective thing, for one thing, and if you find your code more readable, that's fine.

In terms of efficiency, though, I think the while loop probably beats a grep-map-map operation (read in reverse), unless there are other issues I'm not thinking about.