csong@0: '''
csong@0: Author: Chunyang Song
csong@0: Institution: Centre for Digital Music, Queen Mary University of London
csong@0: 
csong@1: '''
csong@20: from basic_functions import repeat, get_note_indices
csong@0: 
csong@2: # To find the product of multiple numbers
csong@1: def cumu_multiply(numbers):
csong@1: 	product = 1
csong@1: 	for n in numbers:
csong@1: 		product = product*n
csong@1: 	return product
csong@0: 
csong@20: #def get_syncopation(seq, subdivision_seq, strong_beat_level, postbar_seq):
csong@20: def get_syncopation(bar, parameters = None):
csong@1: 	syncopation = None
csong@1: 	
csong@20: 	binarySequence = bar.get_binary_sequence()
csong@20: 	sequenceLength = len(binarySequence)
csong@20: 	subdivisionSequence = bar.get_subdivision_sequence()
csong@20: 	strongBeatLevel = bar.get_beat_level()
csong@20: 	nextbarBinarySequence = None
csong@20: 
csong@20: 	if bar.get_next_bar() != None:
csong@20: 		nextbarBinarySequence = bar.get_next_bar().get_binary_sequence()
csong@20: 
csong@20: 	numberOfBeats = cumu_multiply(subdivisionSequence[0:strongBeatLevel+1])	# numberOfBeats is the number of strong beats
csong@2: 	
csong@20: 	if sequenceLength % numberOfBeats != 0:
csong@20: 		print 'Error: the length of sequence is not subdivable by the subdivision factor in subdivision sequence.'
csong@1: 	else:
csong@1: 		# Find the indices of all the strong-beats
csong@20: 		beatIndices = []
csong@20: 		beatInterval = sequenceLength / numberOfBeats
csong@20: 		for i in range(numberOfBeats+1):
csong@20: 			beatIndices.append(i*beatInterval)
csong@20: 		if nextbarBinarySequence != None:		# if there is a postbar_seq, add another two beats index for later calculation
csong@20: 			beatIndices += [sequenceLength+beatInterval, sequenceLength+ 2* beatInterval]
csong@0: 
csong@20: 		noteIndices = get_note_indices(binarySequence)	# all the notes
csong@0: 
csong@1: 		# Calculate the WNBD measure for each note
csong@20: 		def measure_pernote(noteIndices, nextNoteIndex):
csong@1: 			# Find the nearest beats where this note locates - in [beat_indices[j], beat_indices[j+1]) 
csong@1: 			j = 0
csong@20: 			while noteIndices < beatIndices[j] or noteIndices >= beatIndices[j+1]:
csong@1: 				j = j + 1
csong@1: 			
csong@1: 			# The distance of note to nearest beat normalised by the beat interval
csong@20: 			distanceToNearestBeat = min(abs(noteIndices - beatIndices[j]), abs(noteIndices - beatIndices[j+1]))/float(beatInterval)
csong@0: 
csong@1: 			# if this note is on-beat
csong@20: 			if distanceToNearestBeat == 0:	
csong@1: 				measure = 0
csong@1: 			# or if this note is held on past the following beat, but ends on or before the later beat  
csong@20: 			elif beatIndices[j+1] < nextNoteIndex <= beatIndices[j+2]:
csong@20: 				measure = float(2)/distanceToNearestBeat
csong@1: 			else:
csong@20: 				measure = float(1)/distanceToNearestBeat
csong@1: 			return measure
csong@0: 
csong@1: 		total = 0
csong@20: 		for i in range(len(noteIndices)):
csong@20: 			# if this is the last note, end_time is the index of the following note in the next bar
csong@20: 			if i == len(noteIndices)-1:
csong@20: 				# if the next bar is not none or a bar of full rest, 
csong@20: 				# the nextNoteIndex is the sum of sequence length in the current bar and the noteIndex in the next bar
csong@20: 				if nextbarBinarySequence != None and nextbarBinarySequence != repeat([0],len(nextbarBinarySequence)):
csong@20: 					nextNoteIndex = get_note_indices(nextbarBinarySequence)[0]+sequenceLength
csong@20: 				# else when the next bar is none or full rest, end_time is the end of this sequence.
csong@20: 				else:
csong@20: 					nextNoteIndex = sequenceLength
csong@20: 			# else this is not the last note, the nextNoteIndex is the following element in the noteIndices list
csong@0: 			else:
csong@20: 				nextNoteIndex = noteIndices[i+1]
csong@20: 			# sum up the syncopation value for individual note at noteIndices[i]
csong@20: 			total += measure_pernote(noteIndices[i],nextNoteIndex)
csong@0: 
csong@2: 		#syncopation = float(total) / len(note_indices)
csong@0: 
csong@20: 	# return the total value, leave the normalisation done in the end
csong@2: 	return total