csong@0: '''
csong@0: Author: Chunyang Song
csong@0: Institution: Centre for Digital Music, Queen Mary University of London
csong@0: '''
csong@0: 
csong@23: from basic_functions import repeat, subdivide, ceiling, velocity_sequence_to_min_timespan, get_rhythm_category
csong@1: 
csong@12: def get_cost(sequence,nextSequence):
csong@23: 	sequence = velocity_sequence_to_min_timespan(sequence)					# converting to the minimum time-span format
csong@1: 	
csong@12: 	if sequence[1:] == repeat([0],len(sequence)-1):		# null prototype
csong@1: 		cost = 0
csong@12: 	elif sequence == repeat([1],len(sequence)):			# filled prototype
csong@1: 		cost = 1
csong@12: 	elif sequence[0] == 1 and sequence[-1] == 0:			# run1 prototype
csong@1: 		cost = 2
csong@20: 	elif sequence[0] == 1 and (nextSequence == None or nextSequence[0] == 0):	# run2 prototype
csong@1: 		cost = 2
csong@20: 	elif sequence[-1] == 1 and nextSequence != None and nextSequence[0] == 1:		# upbeat prototype
csong@1: 		cost = 3
csong@12: 	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@12: def syncopation_perlevel(subSequences):
christopher@38: 	#print 'subSequences', subSequences
csong@1: 	total = 0
csong@12: 	for l in range(len(subSequences)-1):
christopher@38: 		#print 'cost', get_cost(subSequences[l], subSequences[l+1])
csong@12: 		total = total + get_cost(subSequences[l], subSequences[l+1])
christopher@38: 	#print 'total this level', total
csong@12: 	normalised = float(total)/(len(subSequences)-1)
csong@1: 	
csong@1: 	return normalised
csong@1: 
csong@19: def get_syncopation(bar, parameters = None):
csong@1: 	syncopation = None
csong@12: 
csong@12: 	binarySequence = bar.get_binary_sequence()
csong@12: 	subdivisionSequence = bar.get_subdivision_sequence()
csong@12: 
csong@20: 	# PRS does not handle polyrhythms
csong@12: 	if get_rhythm_category(binarySequence, subdivisionSequence) == 'poly':
csong@12: 		print 'Warning: PRS model detects polyrhythms so returning None.'
csong@0: 	else:
csong@1: 		syncopation = 0
csong@0: 
csong@20: 		# retrieve the binary sequence in the next bar
csong@12: 		if bar.get_next_bar() != None:
csong@12: 			nextbarBinarySequence = bar.get_next_bar().get_binary_sequence()
csong@12: 		else:
csong@12: 			nextbarBinarySequence = None
csong@12: 
csong@20: 		# numberOfSubSeqs is the number of sub-sequences at a certain metrical level, initialised to be 1 (at the bar level)
csong@12: 		numberOfSubSeqs = 1	
csong@12: 		for subdivisor in subdivisionSequence:
csong@20: 			# numberOfSubSeqs is product of all the subdivisors up to the current level
csong@12: 			numberOfSubSeqs = numberOfSubSeqs * subdivisor
csong@20: 			
csong@1: 			# recursion stops when the length of sub-sequence is less than 2
csong@12: 			if len(binarySequence)/numberOfSubSeqs >= 2:		
csong@1: 				# generate sub-sequences and append the next bar sequence
csong@12: 				subSequences = subdivide(ceiling(binarySequence), numberOfSubSeqs)	
csong@12: 				subSequences.append(nextbarBinarySequence)
csong@1: 				# adding syncopation at each metrical level to the total syncopation
csong@20: 				#print 'per level', syncopation_perlevel(subSequences)
csong@12: 				syncopation += syncopation_perlevel(subSequences)	
csong@1: 			else:
csong@1: 				break
csong@0: 
csong@1: 	return syncopation