For an uncookied, no authentication, setup I'd like to color users by their IPs. Not as security or anything, just to distinguish them a bit. My style of problem solving in new domains is woefully brute-trial-and-error and since this seems fun and interesting, I'm putting it up.

I've played around with things like this: 

sub xor_it_together {
  my @ip = shift =~ /(\d+)/g;
  my $code = join'^',@ip;
  print eval "$code";
}
# xor_it_together('67.167.26.54') --> 200
# xor_it_together('127.0.0.1') --> 126

[download]

That could be okay, maybe, for a gray scale; rgb(128,128,128). But different rgb would be nice. So this next bit seems to be passable (a final version should probably add a reproducable random seed, like an IP digest, so that IPs can't be reverse engineered from the colors). 

use List::Util "sum";
sub ip2rgb {
    my @ip = shift =~ /(\d+)/g;
    my $r = eval "@{[ join '^', @ip ]}";
    my $g = sum(@ip) % 255; # left-overs
    my ( $b ) = sort @ip;   # lowest of group
    print "$r, $g, $b";
}
# ip2rgb '220.17.120.164' --> 17, 11, 120
# ip2rgb '127.0.0.1' --> 126, 128, 0

[download]

Any nicer or alternative ideas?

update (20050829-1914): I'm glad I got over my temerity about posting the question. All the answers are cool and I am learning something new from all of them. Thanks!

In reply to Creative presentation algorithm: IP to a color by Your Mother

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