annotate Syncopation models/WNBD.py @ 20:b959c2acb927

Refactored all models except for KTH, all past testing except for SG.

'''
Author: Chunyang Song
Institution: Centre for Digital Music, Queen Mary University of London

'''
from basic_functions import repeat, get_note_indices

# To find the product of multiple numbers
def cumu_multiply(numbers):
	product = 1
	for n in numbers:
		product = product*n
	return product

#def get_syncopation(seq, subdivision_seq, strong_beat_level, postbar_seq):
def get_syncopation(bar, parameters = None):
	syncopation = None
	
	binarySequence = bar.get_binary_sequence()
	sequenceLength = len(binarySequence)
	subdivisionSequence = bar.get_subdivision_sequence()
	strongBeatLevel = bar.get_beat_level()
	nextbarBinarySequence = None

	if bar.get_next_bar() != None:
		nextbarBinarySequence = bar.get_next_bar().get_binary_sequence()

	numberOfBeats = cumu_multiply(subdivisionSequence[0:strongBeatLevel+1])	# numberOfBeats is the number of strong beats
	
	if sequenceLength % numberOfBeats != 0:
		print 'Error: the length of sequence is not subdivable by the subdivision factor in subdivision sequence.'
	else:
		# Find the indices of all the strong-beats
		beatIndices = []
		beatInterval = sequenceLength / numberOfBeats
		for i in range(numberOfBeats+1):
			beatIndices.append(i*beatInterval)
		if nextbarBinarySequence != None:		# if there is a postbar_seq, add another two beats index for later calculation
			beatIndices += [sequenceLength+beatInterval, sequenceLength+ 2* beatInterval]

		noteIndices = get_note_indices(binarySequence)	# all the notes

		# Calculate the WNBD measure for each note
		def measure_pernote(noteIndices, nextNoteIndex):
			# Find the nearest beats where this note locates - in [beat_indices[j], beat_indices[j+1]) 
			j = 0
			while noteIndices < beatIndices[j] or noteIndices >= beatIndices[j+1]:
				j = j + 1
			
			# The distance of note to nearest beat normalised by the beat interval
			distanceToNearestBeat = min(abs(noteIndices - beatIndices[j]), abs(noteIndices - beatIndices[j+1]))/float(beatInterval)

			# if this note is on-beat
			if distanceToNearestBeat == 0:	
				measure = 0
			# or if this note is held on past the following beat, but ends on or before the later beat  
			elif beatIndices[j+1] < nextNoteIndex <= beatIndices[j+2]:
				measure = float(2)/distanceToNearestBeat
			else:
				measure = float(1)/distanceToNearestBeat
			return measure

		total = 0
		for i in range(len(noteIndices)):
			# if this is the last note, end_time is the index of the following note in the next bar
			if i == len(noteIndices)-1:
				# if the next bar is not none or a bar of full rest, 
				# the nextNoteIndex is the sum of sequence length in the current bar and the noteIndex in the next bar
				if nextbarBinarySequence != None and nextbarBinarySequence != repeat([0],len(nextbarBinarySequence)):
					nextNoteIndex = get_note_indices(nextbarBinarySequence)[0]+sequenceLength
				# else when the next bar is none or full rest, end_time is the end of this sequence.
				else:
					nextNoteIndex = sequenceLength
			# else this is not the last note, the nextNoteIndex is the following element in the noteIndices list
			else:
				nextNoteIndex = noteIndices[i+1]
			# sum up the syncopation value for individual note at noteIndices[i]
			total += measure_pernote(noteIndices[i],nextNoteIndex)

		#syncopation = float(total) / len(note_indices)

	# return the total value, leave the normalisation done in the end
	return total