csong@0: '''
csong@0: Author: Chunyang Song
csong@0: Institution: Centre for Digital Music, Queen Mary University of London
csong@0: 
csong@1: '''
csong@2: from BasicFuncs 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@1: def get_syncopation(seq, subdivision_seq, strong_beat_level, postbar_seq):
csong@1: 	syncopation = None
csong@1: 	
csong@1: 	num_beats = cumu_multiply(subdivision_seq[0:strong_beat_level+1])	# num_beats is the number of strong beats
csong@2: 	
csong@1: 	if len(seq)%num_beats != 0:
csong@1: 		print 'Error: the length of sequence is not subdivable by the subdivision factor in subdivision_seq.'
csong@1: 	else:
csong@1: 		# Find the indices of all the strong-beats
csong@1: 		beat_indices = []
csong@1: 		beat_interval = len(seq)/num_beats
csong@1: 		for i in range(num_beats+1):
csong@1: 			beat_indices.append(i*beat_interval)
csong@1: 		if postbar_seq != None:		# if there is a postbar_seq, add another two beats index for later calculation
csong@1: 			beat_indices += [len(seq)+beat_interval, len(seq)+ 2* beat_interval]
csong@0: 
csong@1: 		note_indices = get_note_indices(seq)	# all the notes
csong@0: 
csong@1: 		# Calculate the WNBD measure for each note
csong@1: 		def measure_pernote(note_index, nextnote_index):
csong@1: 			# Find the nearest beats where this note locates - in [beat_indices[j], beat_indices[j+1]) 
csong@1: 			j = 0
csong@1: 			while note_index < beat_indices[j] or note_index >= beat_indices[j+1]:
csong@1: 				j = j + 1
csong@1: 			
csong@1: 			# The distance of note to nearest beat normalised by the beat interval
csong@1: 			distance_nearest_beat = min(abs(note_index - beat_indices[j]), abs(note_index - beat_indices[j+1]))/float(beat_interval)
csong@0: 
csong@1: 			# if this note is on-beat
csong@1: 			if distance_nearest_beat == 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@1: 			elif beat_indices[j+1] < nextnote_index <= beat_indices[j+2]:
csong@1: 				measure = float(2)/distance_nearest_beat
csong@1: 			else:
csong@1: 				measure = float(1)/distance_nearest_beat
csong@0: 
csong@1: 			return measure
csong@0: 
csong@1: 		total = 0
csong@1: 		for i in range(len(note_indices)):
csong@1: 			if i == len(note_indices)-1:# if this is the last note, end_time is the index of the following note in the next bar
csong@1: 				if postbar_seq != None and postbar_seq != repeat([0],len(postbar_seq)):
csong@1: 					nextnote_index = get_note_indices(postbar_seq)[0]+len(seq)
csong@1: 				else:	# or if the next bar is none or full rest, end_time is the end of this sequence.
csong@1: 					nextnote_index = len(seq)
csong@0: 			else:
csong@1: 				nextnote_index = note_indices[i+1]
csong@1: 			total += measure_pernote(note_indices[i],nextnote_index)
csong@0: 
csong@2: 		#syncopation = float(total) / len(note_indices)
csong@0: 
csong@2: 	return total