As part of side-project (inspired by this) to breed Irish jigs (just the 'A' part to start off with), I had the need for a large, random but still 'genetically strong' population of tunes - I was getting bored waiting for 100 generations of random notes to start getting interesting.

To that end, here's a little Markov-chain routine that analyses as many tunes as I could be bothered to type in and then prints "random diddly". The LENGTH constant can be used to refine the length of the chain 'key' - 1 will just pick single random weighted notes from a flat data structure, whereas a setting of 8 or 9 will duplicate an existing tune near-exactly (although some of the more 'symmetrical' tunes) can wrap round a few times before stopping). A setting of 3 or 4 can produce some quite interesting tunes - not structured, but then that's what the breeding will attempt to achieve.

When I get a chance, I'll write a ABC P::RD module so I don't have to type in the data (or play back the notes off the screen on my penny-whistle :) ) - unless anybody can point me in the direction of an existing one.

All suggestions are as ever welcome. 
#!/usr/bin/perl

###########################################
# Variable Length Markov Diddly. 
###########################################

use strict;
use constant LENGTH => 4;                            # length of patte
+rn key

my %probs;                                            # probabilities 
+of next note

while (<DATA>) {                                    # read the existin
+g tunes...
    chomp;
    my @line = split /,/;
    my @notes = ("START") x (LENGTH);                # cyclic buffer
    while (@line) {
        shift (@notes);
        push @notes, shift(@line).",".shift(@line); # "note,length"
        $probs{key(@notes)}{$notes[$#notes]}++;
    }
    shift (@notes);
    $probs{key(@notes)}{"END"}++;
}

my @notes = ("START") x LENGTH;
do {
    shift(@notes);
    my %next = %{$probs{key(@notes)}};                # array of probs
    my @next = map {($_) x $next{$_}} keys %next;    # 1 entry per 'pr
+ob'
    push @notes, $next[int(rand(@next))];
    print "$notes[$#notes] " unless ($notes[$#notes] eq "END");
} while ($notes[$#notes] ne "END");

sub key {return join("",@_[0..LENGTH-2]);}            # make space-sep
+arated key

# a bunch of common session tunes (plus one of mine <g>)
__DATA__
e2,4,e2,2,b2,2,e2,2,b2,2,e2,2,e2,2,b2,2,a2,2,fs2,2,d2,2,e2,4,e2,2,b2,4
+,cs3,2,d3,2,cs3,2,b2,2,a2,2,fs2,2,d2,2,e2,4,e2,2,b2,2,e2,2,b2,2,e2,2,
+e2,2,b2,2,a2,2,fs2,2,d2,2,g2,4,g2,2,fs2,2,g2,2,a2,2,b2,2,a2,2,g2,2,fs
+2,2,e2,2,d2,2
d2,2,g2,2,g2,2,b2,2,g2,2,g2,2,a2,2,g2,2,a2,2,b2,2,g2,2,g2,2,e3,2,g3,2,
+e3,2,d3,2,b2,2,g2,2,a2,2,g2,2,a2,2,b2,2,g2,2,e2,2,d2,2,g2,2,g2,2,b2,2
+,g2,2,g2,2,a2,2,g2,2,a2,2,b2,2,g2,2,g2,2,e3,2,g3,2,e3,2,d3,2,b2,2,g2,
+2,a2,2,g2,2,fs2,2,g2,6
d2,4,d2,2,a2,6,b2,2,a2,2,g2,2,a2,2,b2,2,a2,2,d2,4,d2,2,a2,6,b2,2,a2,2,
+g2,2,e2,2,g2,2,e2,2,d2,4,d2,2,a2,6,b2,2,a2,2,g2,2,a2,2,b2,2,c3,2,d2,2
+,c3,2,b2,2,c3,2,b2,2,a2,2,b2,2,a2,2,g2,2,e2,2,g2,2,e2,2
d3,2,e3,2,d3,2,b2,4,g2,2,a2,4,g2,2,e2,4,d2,2,g2,4,g2,2,g2,2,a2,2,b2,2,
+d3,4,b2,2,a2,6,d3,2,e3,2,d3,2,b2,4,g3,2,fs2,4,e3,2,c3,4,e3,2,d3,2,e3,
+2,d3,2,c3,2,b2,2,a2,2,g2,12
b2,2,g2,2,g2,2,d2,2,g2,2,g2,2,b2,2,g2,2,b2,2,d3,2,c3,2,b2,2,c3,2,a2,2,
+a2,2,fs2,2,a2,2,a2,2,c3,2,a2,2,c3,2,e3,2,d3,2,c3,2,b2,2,g2,2,g2,2,d2,
+2,g2,2,g2,2,b2,2,g2,2,b2,2,d3,2,c3,2,b2,2,c3,2,b2,2,c3,2,a2,2,d3,2,c3
+,2,b2,2,g2,2,g2,2,g2,2,d3,2,c3,2
fs2,4,b2,2,b2,2,cs3,2,d3,2,cs3,4,a2,2,a2,2,b2,2,cs3,2,d3,4,b2,2,b2,2,c
+s3,2,d3,2,e3,2,fs3,2,e3,2,d3,2,cs3,2,b2,2,fs2,4,b2,2,b2,2,cs3,2,d3,2,
+cs3,4,a2,2,a2,2,b2,2,cs3,2,d3,2,cs3,2,d3,2,e3,2,d3,2,e3,2,fs3,2,b2,2,
+b2,2,b2,6
a2,2,fs2,2,a2,2,a2,2,fs2,2,a2,2,b2,2,g2,2,b2,2,b2,2,g2,2,b2,2,a2,2,fs2
+,2,a2,2,a2,2,d3,2,e3,2,fs3,2,e3,2,d3,3,b2,2,d3,2,b2,2,a2,2,fs2,2,a2,2
+,a2,2,fs2,2,a2,2,b2,2,g2,2,b2,2,b2,2,g2,2,b2,2,d3,2,e3,2,fs3,2,a3,2,f
+s3,2,e3,2,fs3,2,b2,2,b2,3,b2,2,d3,2,b2,2
a2,2,d2,2,d2,2,b2,2,d2,2,d2,2,c3,6,c3,2,b2,2,a2,2,g2,2,a2,2,b2,2,a2,2,
+g2,2,fs2,2,g2,2,fs2,2,g2,2,e2,2,fs2,2,g2,2,a2,2,d2,2,d2,2,b2,2,d2,2,d
+2,2,c3,6,c3,2,b2,2,a2,2,g2,2,a2,2,b2,2,a2,2,g2,2,fs2,2,g2,12
e2,2,fs2,2,e2,2,b2,4,b2,2,b2,2,a2,2,fs2,2,d3,6,e2,2,fs2,2,e2,2,b2,4,b2
+,2,b2,2,a2,2,fs2,2,fs2,4,e2,2,e2,2,fs2,2,e2,2,b2,4,b2,2,b2,2,a2,2,fs2
+,2,d3,6,b2,2,cs3,2,d3,2,e3,4,b2,2,b2,2,a2,2,fs2,2,fs2,4,e2,2
d2,4,a2,2,fs2,4,a2,2,d2,4,a2,2,fs2,4,a2,2,d3,4,e3,2,fs3,4,e3,2,d3,4,cs
+3,2,b2,4,a2,2,e3,6,fs3,6,g3,6,fs3,6,e3,4,d3,2,cs3,4,b2,2,a2,2,b2,2,a2
+,2,g2,2,fs2,2,e2,2
d2,4,e2,2,fs2,4,g2,2,a2,4,b2,2,a2,4,fs2,2,a2,4,b2,2,a2,4,fs2,2,a2,4,b2
+,2,a2,4,fs2,2,d2,4,e2,2,fs2,4,g2,2,a2,4,b2,2,a2,4,d3,2,cs3,4,b2,2,a2,
+4,fs2,2,d2,12
g2,2,g2,2,g2,2,g2,6,g2,2,g2,2,g2,2,g2,4,d3,2,b2,4,g2,2,b2,4,d3,2,g3,4,
+d3,2,b2,4,g2,2,d2,2,d2,2,d2,2,d2,6,d2,2,d2,2,d2,2,d2,4,a2,2,fs2,4,d2,
+2,fs2,4,a2,2,c3,4,a2,2,fs2,4,d2,2
a2,6,a2,6,a2,2,fs2,2,d3,2,a2,2,fs2,2,d2,2,g2,6,g2,6,g2,2,e2,2,fs2,2,g3
+,2,fs2,2,e2,2,a2,6,a2,6,a2,2,fs2,2,d3,2,a2,2,fs2,2,d2,2,e2,2,fs2,2,g2
+,2,fs2,2,g2,2,e2,2,d2,12
a2,2,d2,2,d2,2,b2,2,d2,2,d2,2,c3,6,c3,2,b2,2,a2,2,g2,2,a2,2,b2,2,a2,2,
+g2,2,fs2,2,g2,2,fs2,2,g2,2,e2,2,fs2,2,g2,2,a2,2,d2,2,d2,2,b2,2,d2,2,d
+2,2,c3,6,c3,2,b2,2,a2,2,g2,2,a2,2,b2,2,a2,2,g2,2,fs2,2,g2,12

[download]
Cheers,
Ben

In reply to Markov Diddly by benn

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.