BrowserUk:

I used to use a "density map" generator back in the day. Basically each time you want a random coordinate, you generate the coordinate plus one extra random number. You then check the number against a density function, and if the extra random number is less than the density at that location, you return the coordinates. Otherwise you try again:

sub generate_coordinate {
    my $fDensity = shift;
    my @coordinate;
    {
        @coordinate = (rand, rand);
        redo if $fDensity->(rand, @coordinate);
    }
    return @coordinate;
}

sub density_uniform { 1 }
sub density_h_gradient { $_[0] < $_[2] }
sub density_v_gradient { $_[0] < $_[1] }

sub density_broken [ 0 }

sub density_lookup {
    my ($chk, $r, $c) = @_;
    return $lookup_table[$r][$c]<$chk;
}

[download]

So by defining an appropriate density map function, you can create many types of distributions. The disadvantage is that your density map function may reject too many candidates, slowing things down. (The density_broken function, for example, is quite useless in this regard.)

The reason that I thought you might like it is this: For testing a project, I would create distinct distributions by simply drawing an image with MSPAINT or similar and loading that into a lookup table and using a function like density_lookup.

I don't know your objections to your own suggestion, so I don't know if this one is interesting or not, though.

...roboticus

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

In reply to Re: Randomly biased, random numbers. by roboticus
in thread Randomly biased, random numbers. by BrowserUk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.