comparison Syncopation models/synpy/LHL.py @ 45:6e9154fc58df

moving the code files to the synpy package directory

+'''
+Author: Chunyang Song
+Institution: Centre for Digital Music, Queen Mary University of London
+'''
+
+from basic_functions import concatenate, repeat, subdivide, ceiling, get_rhythm_category
+from parameter_setter import are_parameters_valid
+
+terminalNodes = []		# Global variable, storing all the terminal nodes from recursive tree structure in time order
+
+
+
+# Each terminnal node contains two properties: its node type (note or rest) and its metrical weight.
+class Node:
+	def __init__(self,nodeType,metricalWeight):
+		self.nodeType = nodeType
+		self.metricalWeight = metricalWeight
+
+# This function will recurse the tree for a binary sequence and return a sequence containing the terminal nodes in time order.
+def recursive_tree(binarySequence, subdivisionSequence, weightSequence, metricalWeight, level):
+	# If matching to a Note type, add to terminal nodes
+	if binarySequence == concatenate([1],repeat([0],len(binarySequence)-1)):	
+		terminalNodes.append(Node('N',metricalWeight))
+
+	# If matching to a Rest type, add to terminal nodes
+	elif binarySequence == repeat([0],len(binarySequence)):					
+		terminalNodes.append(Node('R',metricalWeight))
+
+	# Keep subdividing by the subdivisor of the next level
+	else:													
+		subBinarySequences = subdivide(binarySequence, subdivisionSequence[level+1])	
+		subWeightSequences = concatenate([metricalWeight],repeat([weightSequence[level+1]],subdivisionSequence[level+1]-1))
+		for a in range(len(subBinarySequences)):
+			recursive_tree(subBinarySequences[a], subdivisionSequence, weightSequence, subWeightSequences[a], level+1)
+
+
+def get_syncopation(bar, parameters = None):
+	del terminalNodes[:]
+	syncopation = None
+
+	binarySequence = bar.get_binary_sequence()
+	subdivisionSequence = bar.get_subdivision_sequence()
+
+	# LHL can only measure monorhythms
+	if get_rhythm_category(binarySequence, subdivisionSequence) == 'poly':
+		print 'Warning: LHL model detects polyrhythms so returning None.'
+	else:
+		# set defaults
+		Lmax = 5
+		weightSequence = range(0,-Lmax-1,-1)
+		# if parameters are specified by users, check their validities and update parameters if valid		
+		if parameters!= None:
+			if 'Lmax' in parameters:
+				Lmax = parameters['Lmax']				
+			if 'W' in parameters:
+				weightSequence = parameters['W']
+
+		if not are_parameters_valid(Lmax, weightSequence, subdivisionSequence):
+			print 'Error: the given parameters are not valid.'
+		else:
+			# If there is rhythm in previous bar, process its tree structure
+			prevbar =  bar.get_previous_bar()
+			if prevbar != None and not prevbar.is_empty():
+				prebarBinarySequence = prevbar.get_binary_sequence()
+				recursive_tree(ceiling(prebarBinarySequence), subdivisionSequence, weightSequence, weightSequence[0],0)
+				
+				if len(terminalNodes)>0:
+					# Only keep the last note-type node
+					while terminalNodes[-1].nodeType != 'N':
+						del terminalNodes[-1]
+					del terminalNodes[0:-1]
+
+			# For the rhythm in the current bar, process its tree structure and store the terminal nodes 
+			recursive_tree(ceiling(binarySequence), subdivisionSequence, weightSequence, weightSequence[0],0)
+			
+			# for t in terminalNodes:
+			# 	print '<', t.nodeType, t.metricalWeight, '>'
+
+			# Search for the NR pairs that contribute to syncopation,then add the weight-difference to the NRpairSyncopation list
+			NRpairSyncopation = []
+			for i in range(len(terminalNodes)-1,0,-1):
+				if terminalNodes[i].nodeType == 'R':
+					for j in range(i-1, -1, -1):
+						if (terminalNodes[j].nodeType == 'N') & (terminalNodes[i].metricalWeight >= terminalNodes[j].metricalWeight):
+							NRpairSyncopation.append(terminalNodes[i].metricalWeight - terminalNodes[j].metricalWeight)
+							break
+			#print NRpairSyncopation
+
+			# If there are syncopation, sum all the local syncopation values stored in NRpairSyncopation list	
+			if len(NRpairSyncopation) != 0:
+				syncopation = sum(NRpairSyncopation)
+			# If no syncopation, the value is -1; 	
+			elif len(terminalNodes) != 0:
+				syncopation = -1
+
+	return syncopation
+
+