It's too bad there's no easy mechanism for creating a hash value pointing to a hash key, instead of another hash value.
Does it buy anything to create a hash with keys of some known hash function, and values as indexes pointing into an array? There's one more lookup, but into an array, which should be much cheaper than another hash lookup.
#!/usr/bin/env perl
use strict;
use warnings;
use Devel::Size qw(size total_size);
my $num = 0;
my %hashed_keys;
my @values = ();
for my $word ('aaaa'..'zzzz') {
# Store $word -> $num
my $hash_word = some_hash($word);
my $hash_word_index = scalar @values;
$hashed_keys{$hash_word} = $hash_word_index;
push @values, $num;
# Store $num -> $word
my $hash_num = some_hash($num);
my $hash_num_index = scalar @values;
$hashed_keys{$hash_num} = $hash_num_index;
push @values, $word;
++$num;
}
sub some_hash {
return shift;
}
my $total_size;
for my $var (\%hashed_keys, \@values) {
my $tsize = total_size($var);
printf "%s\n", total_size($var);
$total_size += $tsize;
}
print "total: $total_size\n";
exit;
Without a real hash function, this gives:
43383174
29785044
total: 73168218
...which is only slightly smaller than your original 2-hash result. Mind you, I'm on a 32-bit perl, so that could be the difference.
(Caveats: I've not used a real hash function. I've not accounted for hash collisions.)
-QM
--
Quantum Mechanics: The dreams stuff is made of
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.