csong@0: '''
csong@0: Author: Chunyang Song
csong@0: Institution: Centre for Digital Music, Queen Mary University of London
csong@0: '''
csong@0: 
csong@14: from basic_functions import repeat, subdivide, ceiling, get_min_timeSpan, get_rhythm_category
csong@1: 
csong@14: def get_cost(sequence,nextSequence):
csong@14: 	sequence = get_min_timeSpan(sequence)					# converting to the minimum time-span format
csong@1: 	
csong@14: 	if sequence[1:] == repeat([0],len(sequence)-1):		# null prototype
csong@1: 		cost = 0
csong@14: 	elif sequence == repeat([1],len(sequence)):			# filled prototype
csong@1: 		cost = 1
csong@14: 	elif sequence[0] == 1 and sequence[-1] == 0:			# run1 prototype
csong@1: 		cost = 2
csong@14: 	elif sequence[0] == 1 and (nextSequence == None or nenextSequencext_seq[0] == 0):	# run2 prototype
csong@1: 		cost = 2
csong@14: 	elif sequence[0] == 1 and sequence[-1] == 1 and nextSequence != None and nextSequence[0] == 1:		# upbeat prototype
csong@1: 		cost = 3
csong@14: 	elif sequence[0] == 0:							# syncopated prototype
csong@1: 		cost = 5
csong@1: 
csong@1: 	return cost
csong@1: 
csong@1: # This function calculates the syncopation value (cost) for the sequence with the postbar_seq for a certain level. 
csong@14: def syncopation_perlevel(subSequences):
csong@1: 	total = 0
csong@14: 	for l in range(len(subSequences)-1):
csong@14: 		total = total + get_cost(subSequences[l], subSequences[l+1])
csong@14: 	normalised = float(total)/(len(subSequences)-1)
csong@1: 	
csong@1: 	return normalised
csong@1: 
csong@14: #def get_syncopation(seq,subdivision_seq, postbar_seq, rhythm_category):
csong@14: def get_syncopation(bar, weightSequence = None, LMax = None):
csong@14: 	'''
csong@14: 	The get_syncopation function calculates the overall syncopation value for a bar of sequence.
csong@14: 	'''
csong@1: 	syncopation = None
csong@14: 
csong@14: 	binarySequence = bar.get_binary_sequence()
csong@14: 	subdivisionSequence = bar.get_subdivision_sequence()
csong@14: 
csong@14: 	if get_rhythm_category(binarySequence, subdivisionSequence) == 'poly':
csong@14: 		print 'Warning: PRS model detects polyrhythms so returning None.'
csong@0: 	else:
csong@1: 		syncopation = 0
csong@0: 
csong@14: 		if bar.get_next_bar() != None:
csong@14: 			nextbarBinarySequence = bar.get_next_bar().get_binary_sequence()
csong@14: 		else:
csong@14: 			nextbarBinarySequence = None
csong@14: 
csong@14: 		# the initial number of sub-sequences at a certain metrical level
csong@14: 		numberOfSubSeqs = 1	
csong@14: 		for subdivisor in subdivisionSequence:
csong@1: 			# the number of sub-sequence at the current level is product of all the subdivisors up to the current level
csong@14: 			numberOfSubSeqs = numberOfSubSeqs * subdivisor
csong@1: 			# recursion stops when the length of sub-sequence is less than 2
csong@14: 			if len(binarySequence)/numberOfSubSeqs >= 2:		
csong@1: 				# generate sub-sequences and append the next bar sequence
csong@14: 				subSequences = subdivide(ceiling(binarySequence), numberOfSubSeqs)	
csong@14: 				subSequences.append(nextbarBinarySequence)
csong@1: 				# adding syncopation at each metrical level to the total syncopation
csong@14: 				syncopation += syncopation_perlevel(subSequences)	
csong@1: 			else:
csong@1: 				break
csong@0: 
csong@1: 	return syncopation