BrowserUk:

Here's another idea that occurred to me, so I thought I'd toss it out--build a function that generates a coordinate and then randomly maps it into a "clump" for you. In order to prevent any of your area from being ignored, there's also a chance that it won't be mapped to a clump:

#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

sub generate_clumpy_rand {
    my $num = shift // int(10*rand()+3);
    my @clumps;
    print "Generator has $num clumps\n";
    for my $i (1 .. $num) {
        my @center_size = (rand, rand, rand, rand);
        print "clump 1 centered at ($center_size[0],$center_size[1]) "
        .     "size is $center_size[2]x$center_size[3]\n";
        push @clumps, \@center_size;
    }
    return sub {
        my @coord = (rand, rand);

        # Ensure we have a background of random dots over entire regio
+n
        return @coord if (.1 > rand);

        # Choose a clump, and map the coordinate into that clump
        my @clump = @{$clumps[rand @clumps]};
        return (
            ($coord[0]*$clump[2])+$clump[0],
            ($coord[1]*$clump[3])+$clump[1]
        );
    }
}

my $clump_rand = generate_clumpy_rand(1);
my @coord = $clumpy_rand->();
print Dumper(\@coord);
[download]

The good point is that it's simple and fast. It's a proof-of-concept, though, and I didn't do any work to ensure that the clumps don't extend beyond the desired range. If you like the idea, then that task is left as an exercise for the reader ;^D.

Update: I forgot to mention: The clumps in this version are rectangular. Changing their shape is possible, but I didn't bother doing that, either.

...roboticus

When your only tool is a hammer, all problems look like your thumb.