Euclidean rhythms: Björklund's algorithm in Python 3

bjorklund.py

#!/usr/bin/env python3

# Copyright (c) 2011 Brian House
# https://github.com/brianhouse/bjorklund

# Copyright (c) 2017 Tom Hensel
# 

import argparse
import sys

parser = argparse.ArgumentParser(description='Euclidean rhythms: Björklund''s algorithm in Python 3')
parser.add_argument('-p', '--pulses', dest='pulses', type=int, default=5, help='pulse count')
parser.add_argument('-s', '--steps', dest='steps', type=int, default=13, help='step count')
args = parser.parse_args()

class Bjorklund():
    def __init__(self, steps : int, pulses : int):
        if pulses > steps:
            raise ValueError    
        self.pattern = []
        level = 0
        counts = []
        remainders = []
        divisor = steps - pulses

        remainders.append(pulses)
        while True:
            counts.append(divisor / remainders[level])
            remainders.append(divisor % remainders[level])
            divisor = remainders[level]
            level += 1
            if remainders[level] < 2:
                break
        counts.append(divisor)

        def build(level : int):
            if level == -1:
                self.pattern.append(0)
            elif level == -2:
                self.pattern.append(1)
            else:
                # recursion
                for i in range(0, int(counts[level])):
                    build(level - 1)
                if remainders[level] != 0:
                    build(level - 2)
        build(level)
        i = self.pattern.index(1)
        self.pattern = self.pattern[i:] + self.pattern[0:i]

if __name__ == "__main__":
    try:
        b = Bjorklund(args.steps, args.pulses)
        print(b.pattern)
    except ValueError:
        print('equal or more steps than pulses required!', file=sys.stderr)
        sys.exit(1)