Generates short piano compositions with cellular automata and saves them in MIDI format.

cellular_songs.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

#Command line utility to generate MIDI music intended for piano/piano-like synthesizers with cellular automata. 
import random, click, pygame, time, sys, keyboard
import pygame.midi
from pygame.locals import *
from midiutil.MidiFile import MIDIFile

#pentatonic scales
MAJOR_SCALE = [60, 62, 64, 67, 69]
MINOR_SCALE = [60, 63, 65, 67, 70]

#function that takes in a cell index and the last row and outputs a value according to wolfram rule 90
def evaluate(i, last_row):
	left = "0"
	middle = str(last_row[i])
	right = "0"

	if i == 0:
		left = str(random.randint(0, 1))
	else:
		left = str(last_row[i - 1])

	if i == len(last_row) - 1:
		right = str(random.randint(0, 1))
	else:
		right = str(last_row[i + 1])

	state = left + middle + right

	if state == "111":
		return 0
	elif state == "110":
		return 1
	elif state == "101":
		return 0
	elif state == "100":
		return 1
	elif state == "011":
		return 1
	elif state == "010":
		return 0
	elif state == "001":
		return 1
	elif state == "000":
		return 0

#get the "sheet music". generates a 1d cellular automata over however many beats you want
def get_automata(voices, beats):
	cells = []
	cells.append([])
	for i in range(voices):
		cells[0].append(random.randint(0, 1))

	for i in range(1, beats):
		cells.append([])
		row = cells[i]
		last_row = cells[i - 1]

		for i in range(voices):
			row.append(evaluate(i, last_row))

	return cells


@click.command()
@click.option('--tempo', default=120, help="Tempo of the song.")
@click.option('--bars', default=12, help="Number of measures in the song. Has no effect in stream mode.")
@click.option('--scale', default="major", help="Major or minor scale.")
@click.option('--stream', default=False, help="Should we stream the output direct to midi?")
@click.option('--port', default=3, help="Device port that your synth is on. Only has effect in stream mode. I have no idea how to figure this out, just try numbers until it works.")
#where the magic happens
def make_song(tempo, bars, scale, stream, port):
	pitches = []

	if scale == 'major':
		pitches = MAJOR_SCALE
	elif scale == 'minor':
		pitches = MINOR_SCALE

	if not stream:
		mf = MIDIFile(1, adjust_origin=True)
		beats = bars * 4 #we're working in 4/4 time here

		automata = get_automata(len(pitches), beats)

		mf.addTrackName(0, 0, "Lead")
		mf.addTempo(0, 0, tempo)

		#for every note in the scale, figure out the pattern of note lengths.
		for i in range(len(pitches)):
			beat = 0
			note_length = 0
			while beat < beats:
				if automata[beat][i] == 1: 
					note_length += 1
				elif (automata[beat][i] == 0 or beat == beats) and note_length > 0:
					mf.addNote(0, 0, pitches[i], beat - note_length, note_length, 100)
					note_length = 0

				beat += 1

		#write to a file.
		file_name = 'song-{}.mid'.format(random.randint(1000, 9999))
		with open(file_name, 'wb') as f:
			mf.writeFile(f)
			print("Saved as", file_name)
	else:
		#pygame is, no joke, the best way to output midi from your computer to a synthesizer (as far as i know)
		pygame.init()
		pygame.midi.init()

		midi_out = pygame.midi.Output(port, 0)
		cells = []

		#get our seed row
		cells.append([])
		for v in range(len(pitches)):
			cells[0].append(random.randint(0, 1))

		i = 0
		new_time = time.time() * 1000
		old_time = time.time() * 1000
		timer = 0
		delay = 1/(tempo/60)

		run = True
		print("Push escape to end playback.")
		while run:
			pygame.event.pump()
			old_time = new_time
			new_time = time.time() * 1000
			delta_time = (new_time - old_time) / 1000
			timer += delta_time

			try:
				if keyboard.is_pressed('escape'):
					run = False
			except:
				pass

			#every time there's a new beat, turn on and off notes as appropriate
			if timer >= delay:
				timer = 0
				for v in range(len(pitches)):
					if cells[i][v] == 1:
						midi_out.note_on(pitches[v], 100)
					else:
						midi_out.note_off(pitches[v])

				i += 1
				cells.append([])
				row = cells[i]
				last_row = cells[i - 1]

				for v in range(len(pitches)):
					row.append(evaluate(v, last_row))

		#make sure we turn off all the notes so it doesn't keep playing without input
		for v in range(len(pitches)):
			midi_out.note_off(pitches[v])
		pygame.midi.quit()
		sys.exit()
	

if __name__ == '__main__':
	make_song()

LICENSE.txt

Copyright (c) 2017 Emma Lugo

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.