csong@0: '''
csong@0: Author: Chunyang Song
csong@0: Institution: Centre for Digital Music, Queen Mary University of London
csong@1: '''
csong@0: 
csong@1: from basic_functions import concatenate, repeat, subdivide, ceiling
csong@0: 
csong@1: terminal_nodes = []		# Global variable, storing all the terminal nodes from recursive tree structure in time order
csong@0: 
csong@1: # Each terminnal node contains two properties: its node type (note or rest) and its metrical weight.
csong@1: class Node:
csong@1: 	def __init__(self,node_type,metrical_weight):
csong@1: 		self.node_type = node_type
csong@1: 		self.metrical_weight = metrical_weight
csong@0: 
csong@1: # This function will recurse the tree for a binary sequence and return a sequence containing the terminal nodes in time order.
csong@1: def recursive_tree(seq, subdivision_seq, weight_seq, metrical_weight, level):
csong@1: 	if seq == concatenate([1],repeat([0],len(seq)-1)):	# If matching to a Note type, add to terminal nodes
csong@1: 		terminal_nodes.append(Node('N',metrical_weight))
csong@0: 
csong@1: 	elif seq == repeat([0],len(seq)):					# If matching to a Rest type, add to terminal nodes
csong@1: 		terminal_nodes.append(Node('R',metrical_weight))
csong@0: 
csong@1: 	else:													# Keep subdividing by the subdivisor of the next level
csong@1: 		sub_seq = subdivide(seq, subdivision_seq[level+1])	
csong@1: 		sub_weight_seq = concatenate([metrical_weight],repeat([weight_seq[level+1]],subdivision_seq[level+1]-1))
csong@1: 		for a in range(len(sub_seq)):
csong@1: 			recursive_tree(sub_seq[a], subdivision_seq, weight_seq, sub_weight_seq[a], level+1)
csong@0: 
csong@1: # This function calculate syncoaption score for LHL model. 
csong@1: def get_syncopation(seq, subdivision_seq, weight_seq, prebar_seq, rhythm_category):
csong@1: 	syncopation = None
csong@1: 	if rhythm_category == 'poly':
csong@1: 		print 'Error: LHL model cannot deal with polyrhythms.'
csong@1: 	else:
csong@1: 		# If there is rhythm in previous bar, process its tree structure
csong@1: 		if prebar_seq != None:		
csong@1: 			recursive_tree(ceiling(prebar_seq), subdivision_seq, weight_seq, weight_seq[0],0)
csong@1: 			
csong@1: 			# Only keep the last note-type node
csong@1: 			while terminal_nodes[-1].node_type != 'N':
csong@1: 				del terminal_nodes[-1]
csong@1: 			del terminal_nodes[0:-1]
csong@0: 
csong@1: 		# For the rhythm in the current bar, process its tree structure and store the terminal nodes 
csong@1: 		recursive_tree(ceiling(seq), subdivision_seq, weight_seq, weight_seq[0],0)
csong@1: 		
csong@1: 		# for t in terminal_nodes:
csong@1: 		# 	print '<', t.node_type, t.metrical_weight, '>'
csong@0: 
csong@1: 		# Search for the NR pairs that contribute to syncopation, add the weight-difference to the NR_pair_syncopation list
csong@1: 		NR_pair_syncopation = []
csong@1: 		for i in range(len(terminal_nodes)-1,0,-1):
csong@1: 			if terminal_nodes[i].node_type == 'R':
csong@1: 				for j in range(i-1, -1, -1):
csong@1: 					if (terminal_nodes[j].node_type == 'N') & (terminal_nodes[i].metrical_weight >= terminal_nodes[j].metrical_weight):
csong@1: 						NR_pair_syncopation.append(terminal_nodes[i].metrical_weight - terminal_nodes[j].metrical_weight)
csong@1: 						break
csong@1: 		#print NR_pair_syncopation
csong@0: 
csong@1: 		# If no syncopation, the value is -1; otherwise, sum all the local syncopation values stored in NR_pair_syncopation list	
csong@1: 		if len(NR_pair_syncopation) != 0:
csong@1: 			syncopation = sum(NR_pair_syncopation)	
csong@1: 		elif len(terminal_nodes) != 0:
csong@1: 			syncopation = -1
csong@0: 
csong@1: 	return syncopation