christopher@45: '''
christopher@45: Author: Chunyang Song
christopher@45: Institution: Centre for Digital Music, Queen Mary University of London
christopher@45: 
christopher@45: '''
christopher@45: 
christopher@45: from basic_functions import ceiling, find_divisor, is_prime, velocity_sequence_to_min_timespan
christopher@45: 
christopher@45: def get_syncopation(bar, parameters = None):
christopher@45: 	binarySequence = velocity_sequence_to_min_timespan(bar.get_binary_sequence())
christopher@45: 	sequenceLength = len(binarySequence)
christopher@45: 
christopher@45: 	syncopation = 0
christopher@45: 
christopher@45: 	# if the length of b_sequence is 1 or a prime number, syncopation is 0;
christopher@45: 	# otherwise the syncopation is calculated by adding up the number of off-beat notes
christopher@45: 	if not ( (sequenceLength == 1) or (is_prime(sequenceLength)) ):
christopher@45: 		# find all the divisors other than 1 and the length of this sequence
christopher@45: 		divisors = find_divisor(sequenceLength)		
christopher@45: 		del divisors[0]
christopher@45: 		del divisors[-1]
christopher@45: 
christopher@45: 		# the on-beat/off-beat positions are the ones that can/cannot be subdivided by the sequenceLength;
christopher@45: 		# the on-beat positions are set to be 0, off-beat positions are set to be 1
christopher@45: 		offbeatness = [1]*sequenceLength			
christopher@45: 		for index in range(sequenceLength):
christopher@45: 			for d in divisors:
christopher@45: 				if index % d == 0:
christopher@45: 					offbeatness[index] = 0
christopher@45: 					break
christopher@45: 			#print 'offbeatness', offbeatness
christopher@45: 			# syncopation is the sum of the hadamard-product of the rhythm binary-sequence and the off-beatness 
christopher@45: 			syncopation += binarySequence[index]*offbeatness[index]
christopher@45: 	
christopher@45: 	return syncopation