def halt(population, generation_count):
"""
Given a population of candidate solutions and generation count (the
number of epochs the algorithm has run) will return a boolean to
indicate if an acceptable solution has been found within the referenced
population.
"""
fittest = population[0].chromosome
suspensions = 0
for i in range(1, len(fittest) - 2):
# Check for a suspension.
if is_suspension(fittest, i, cantus_firmus):
suspensions += 1
return (population[0].fitness >= MAX_REWARD + suspensions or
generation_count > DEFAULT_MAX_GENERATION)
def halt(population, generation_count):
"""
Given a population of candidate solutions and generation count (the
number of epochs the algorithm has run) will return a boolean to
indicate if an acceptable solution has been found within the referenced
population.
"""
fittest = population[0].chromosome
suspensions = 0
for i in range(1, len(fittest) - 2):
# Check for a suspension.
if is_suspension(fittest, i, cantus_firmus):
suspensions += 1
return (population[0].fitness >= MAX_REWARD + suspensions
or generation_count > DEFAULT_MAX_GENERATION)
def fitness_function(genome):
"""
Given a candidate solution will return its fitness score assuming
the cantus_firmus in this closure. Caches the fitness score in the
genome.
"""
# Save some time!
if genome.fitness is not None:
return genome.fitness
# The fitness score to be returned.
fitness_score = 0.0
# Counts the number of repeated notes in the contrapunctus.
repeats = 0
# Counts consecutive parallel thirds.
thirds = 0
# Counts consecutive parallel sixths.
sixths = 0
# Counts the amount of parallel motion.
parallel_motion = 0
# Counts the number of jumps in the melodic contour.
jump_contour = 0
contrapunctus = genome.chromosome
# Make sure the solution starts correctly (at a 5th or octave).
first_interval = contrapunctus[0] - cantus_firmus[0]
if first_interval == 7 or first_interval == 4:
fitness_score += REWARD_FIRST
else:
fitness_score -= PUNISH_FIRST
# Make sure the solution finishes correctly (at an octave).
if contrapunctus[-1] - cantus_firmus[-1] == 7:
fitness_score += REWARD_LAST
else:
fitness_score -= PUNISH_LAST
# Ensure the penultimate note is step wise onto the final note.
if abs(contrapunctus[-1] - contrapunctus[-2]) == 1:
fitness_score += REWARD_LAST_STEP
else:
fitness_score -= PUNISH_LAST_STEP
# Reward contrary motion onto the final note.
cantus_firmus_motion = cantus_firmus[-1] - cantus_firmus[-2]
contrapunctus_motion = contrapunctus[-1] - contrapunctus[-2]
if ((cantus_firmus_motion < 0 and contrapunctus_motion > 0) or
(cantus_firmus_motion > 0 and contrapunctus_motion < 0)):
fitness_score += REWARD_LAST_MOTION
else:
fitness_score -= PUNISH_LAST_MOTION
# Make sure the penultimate note isn't a repeated note.
penultimate_preparation = abs(contrapunctus[-2] - contrapunctus[-3])
if penultimate_preparation == 0:
fitness_score -= PUNISH_REPEATED_PENULTIMATE
else:
# Make sure the movement to the penultimate note isn't from too
# far away (not greater than a third).
if penultimate_preparation < 2:
fitness_score += REWARD_PENULTIMATE_PREPARATION
else:
fitness_score -= PUNISH_PENULTIMATE_PREPARATION
# Check the fitness of the body of the solution.
solution = zip(contrapunctus, cantus_firmus)
last_notes = solution.pop()
last_interval = last_notes[0] - last_notes[1]
for i in range(1, len(solution) - 2):
current_notes = solution[i]
contrapunctus_note, cantus_firmus_note = current_notes
current_interval = contrapunctus_note - cantus_firmus_note
# Punish parallel fifths or octaves.
if ((current_interval == 4 or current_interval == 7) and
(last_interval == 4 or last_interval == 7)):
fitness_score -= PUNISH_PARALLEL_FIFTHS_OCTAVES
# Check if the melody is a repeating note.
if contrapunctus_note == last_notes[0]:
repeats += 1
# Check for a suspension.
if is_suspension(contrapunctus, i, cantus_firmus):
fitness_score += REWARD_SUSPENSION
last_notes = current_notes
last_interval = current_interval
# Punish too many (> 1/3) repeated notes.
if repeats > repeat_threshold:
fitness_score -= PUNISH_REPEATS
genome.fitness = fitness_score
return fitness_score
def fitness_function(genome):
"""
Given a candidate solution will return its fitness score assuming
the cantus_firmus in this closure. Caches the fitness score in the
genome.
"""
# Save some time!
if genome.fitness is not None:
return genome.fitness
# The fitness score to be returned.
fitness_score = 0.0
# Counts the number of repeated notes in the contrapunctus.
repeats = 0
# Counts consecutive parallel thirds.
thirds = 0
# Counts consecutive parallel sixths.
sixths = 0
# Counts the amount of parallel motion.
parallel_motion = 0
# Counts the number of jumps in the melodic contour.
jump_contour = 0
contrapunctus = genome.chromosome
# Make sure the solution starts correctly (at a 5th or octave).
first_interval = contrapunctus[0] - cantus_firmus[0]
if first_interval == 7 or first_interval == 4:
fitness_score += REWARD_FIRST
else:
fitness_score -= PUNISH_FIRST
# Make sure the solution finishes correctly (at an octave).
if contrapunctus[-1] - cantus_firmus[-1] == 7:
fitness_score += REWARD_LAST
else:
fitness_score -= PUNISH_LAST
# Ensure the penultimate note is step wise onto the final note.
if abs(contrapunctus[-1] - contrapunctus[-2]) == 1:
fitness_score += REWARD_LAST_STEP
else:
fitness_score -= PUNISH_LAST_STEP
# Reward contrary motion onto the final note.
cantus_firmus_motion = cantus_firmus[-1] - cantus_firmus[-2]
contrapunctus_motion = contrapunctus[-1] - contrapunctus[-2]
if ((cantus_firmus_motion < 0 and contrapunctus_motion > 0)
or (cantus_firmus_motion > 0 and contrapunctus_motion < 0)):
fitness_score += REWARD_LAST_MOTION
else:
fitness_score -= PUNISH_LAST_MOTION
# Make sure the penultimate note isn't a repeated note.
penultimate_preparation = abs(contrapunctus[-2] - contrapunctus[-3])
if penultimate_preparation == 0:
fitness_score -= PUNISH_REPEATED_PENULTIMATE
else:
# Make sure the movement to the penultimate note isn't from too
# far away (not greater than a third).
if penultimate_preparation < 2:
fitness_score += REWARD_PENULTIMATE_PREPARATION
else:
fitness_score -= PUNISH_PENULTIMATE_PREPARATION
# Check the fitness of the body of the solution.
solution = zip(contrapunctus, cantus_firmus)
last_notes = solution.pop()
last_interval = last_notes[0] - last_notes[1]
for i in range(1, len(solution) - 2):
current_notes = solution[i]
contrapunctus_note, cantus_firmus_note = current_notes
current_interval = contrapunctus_note - cantus_firmus_note
# Punish parallel fifths or octaves.
if ((current_interval == 4 or current_interval == 7)
and (last_interval == 4 or last_interval == 7)):
fitness_score -= PUNISH_PARALLEL_FIFTHS_OCTAVES
# Check if the melody is a repeating note.
if contrapunctus_note == last_notes[0]:
repeats += 1
# Check for a suspension.
if is_suspension(contrapunctus, i, cantus_firmus):
fitness_score += REWARD_SUSPENSION
last_notes = current_notes
last_interval = current_interval
# Punish too many (> 1/3) repeated notes.
if repeats > repeat_threshold:
fitness_score -= PUNISH_REPEATS
genome.fitness = fitness_score
return fitness_score