root / globecomm / heuristic_bc / heuristic_betweenness_centrality.py @ bd3d6dca
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# Implement the section IV in Puzis 2012 paper


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# straight_lineent the section IV in Puzis 2012 paper

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# Heuristic Betweenness Centrality  Partitioning to Biconnected Components

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import os 
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import sys 
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import pprint 
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import networkx as nx 
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import betweenness_centrality as centrality 
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import utility 
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from pdb import set_trace as debugger 
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MAIN_CODE_DIR = os.environ.get('MAIN_CODE_DIR', '') 
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class HeuristicBetweennessCentrality(): 
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def __init__(self, graph): 
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if not nx.is_connected(graph): 
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print "Graph is not connected" 
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sys.exit() 
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self.subgraphs = list(nx.biconnected_component_subgraphs(graph)) 
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self.bicomponents = list(nx.biconnected_components(graph)) 
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self.cutpoints = set(nx.articulation_points(graph)) 
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self.num_vertices = nx.number_of_nodes(graph)

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self.link_weight = LinkWeight(graph, self.bicomponents, self.cutpoints) 
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self.traffic_matrix = TrafficMatrix(self.bicomponents, self.cutpoints, self.link_weight) 
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self.bc_components = list() 
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self.calculate_bc_non_cutpoint()

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self.calculate_bc_cutpoint()

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self.bc = dict() 
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self.finalize()

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def calculate_bc_non_cutpoint(self): 
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"""BC for non cutpoint

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"""

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for i, subgraph in enumerate(self.subgraphs): 
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traffic_matrix = self.traffic_matrix[i]

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cut_without = self.num_vertices  nx.number_of_nodes(subgraph)

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results = centrality.weight_betweenness_centrality(subgraph, traffic_matrix, cut_without) 
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self.bc_components.append(results)

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def calculate_bc_cutpoint(self): 
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self.bc_cutpoints = dict() 
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bc_inter = dict()

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for v in self.cutpoints: 
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inter = 0

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for i, comp in enumerate(self.bicomponents): 
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if v in comp: 
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inter += self.link_weight.get_link_weight(i, v

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) * self.link_weight.get_reverse_link_weight(i, v)

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bc_inter[v] = inter 
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for v in self.cutpoints: 
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bc_locally = 0

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for i, comp in enumerate(self.bicomponents): 
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if v in comp: 
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bc_locally += self.bc_components[i][v]

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self.bc_cutpoints[v] = bc_locally  bc_inter[v]

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# TODO: do not minus the bc_inter

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# self.bc_cutpoints[v] = bc_locally

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def finalize(self): 
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# Add the bc for non cutpoint vertices

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for bc_component in self.bc_components: 
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for key, value in bc_component.iteritems(): 
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if key not in self.bc: 
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self.bc[key] = value

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# Add the bc for cutpoint vertices

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for key, value in self.bc_cutpoints.iteritems(): 
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self.bc[key] = value

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# Rescale the bc according to the original graph

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factor = 1.0 / ((self.num_vertices  1) * (self.num_vertices  2)) 
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# TODO: check the scaling factor, how much should it be?

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# factor = 2.0 / (self.num_vertices*self.num_vertices  3 * self.num_vertices + 2)

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for key, value in self.bc.iteritems(): 
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self.bc[key] = value * factor

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def __str__(self): 
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return str(self.bc) 
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def write(self, filepath): 
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print "HBC score is written to %s" % filepath 
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with open(filepath, 'w') as output: 
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for node, centrality in self.bc.iteritems(): 
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output.write('%s, %s\n' % (node, centrality))

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class TrafficMatrix(): 
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def __init__(self, bicomponents, cutpoints, link_weight): 
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self.bicomponents = bicomponents

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self.cutpoints = cutpoints

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self.num_components = len(bicomponents) 
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self.link_weight = link_weight

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self.h = list() 
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self.generate_empty_traffic_matrix()

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self.generate_traffic_matrix()

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def generate_empty_traffic_matrix(self): 
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for i in range(self.num_components): 
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l = len(self.bicomponents[i]) 
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matrix = [[1 for x in range(l)] for y in range(l)] 
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# update the main diagonal

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for x in range(l): 
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matrix[x][x] = 0

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self.h.append(matrix)

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def generate_traffic_matrix(self): 
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# Update the value when one vertex is a cutpoint, another vertex is not a cutpoint

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for i, components in enumerate(self.bicomponents): 
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normal_points = components.difference(self.cutpoints)

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cutpoints = self.cutpoints.intersection(components)

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for cutpoint in cutpoints: 
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for normal_point in normal_points: 
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communication_intensity = self.link_weight.get_reverse_link_weight(i, cutpoint) + 1 
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self.update(i, cutpoint, normal_point, communication_intensity)

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# Update the value when both vertices are cutpoints

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for i, components in enumerate(self.bicomponents): 
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cutpoints = list(self.cutpoints.intersection(components)) 
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len_cutpoints = len(cutpoints)

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if len_cutpoints > 1: 
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for k in range(len_cutpoints  1): 
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for l in range(1, len_cutpoints): 
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if k == l:

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continue

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communication_intensity = ( 
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self.link_weight.get_reverse_link_weight(i, cutpoints[k]) + 1) * ( 
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self.link_weight.get_reverse_link_weight(i, cutpoints[l]) + 1 
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) 
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self.update(i, cutpoints[k], cutpoints[l], communication_intensity)

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def simple_update(self, comp_index, x_pos, y_pos, value): 
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self.h[comp_index][x_pos][y_pos] = value

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# to keep the symmetric property of Traffic Matrix

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self.h[comp_index][y_pos][x_pos] = value

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def update(self, comp_index, x, y, value): 
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comp = sorted(self.bicomponents[comp_index]) 
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try:

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x_pos = list(comp).index(x)

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y_pos = list(comp).index(y)

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except:

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debugger() 
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a = 2

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self.simple_update(comp_index, x_pos, y_pos, value)

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def __str__(self): 
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return str(self.h) 
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def __getitem__(self, key): 
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return self.h[key] 
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class LinkWeight(): 
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def __init__(self, graph, bicomponents, cutpoints): 
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self.num_vertices = nx.number_of_nodes(graph)

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self.bicomponents = bicomponents

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self.num_components = len(bicomponents) 
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self.cutpoints = cutpoints

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self.Dv_B = [dict() for i in range(self.num_components)] # link weight 
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self.compute_component_tree_weight()

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self.reverse_Dv_B = [dict() for i in range(self.num_components)] # reverse link weight 
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self.generate_reverse_link_weight()

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def _components_sharing_cutpoint(self, B_cutpoints, point): 
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indices = list()

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for i, cp in enumerate(B_cutpoints): 
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if point in cp: 
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indices.append(i) 
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return indices

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def get_link_weight(self, comp_index, point): 
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Dv_B_comp = self.Dv_B[comp_index]

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if point in Dv_B_comp: 
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return Dv_B_comp[point]

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else:

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return 0 
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def set_link_weight(self, comp_index, point, value): 
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self.Dv_B[comp_index][point] = value

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def get_reverse_link_weight(self, comp_index, point): 
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reverse_Dv_B_comp = self.reverse_Dv_B[comp_index]

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if point in reverse_Dv_B_comp: 
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return reverse_Dv_B_comp[point]

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else:

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return 0 
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def generate_reverse_link_weight(self): 
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for i, Dv_B_i in enumerate(self.Dv_B): 
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for key, value in Dv_B_i.iteritems(): 
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self.reverse_Dv_B[i][key] = self.num_vertices  1  self.get_link_weight(i, key) 
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def compute_component_tree_weight(self): 
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"""Follows exactly the Algorithm 1 [Puzis 2012]

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"""

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B_cutpoints = list() # number of cutpoints in component B 
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for comp in self.bicomponents: 
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points = comp.intersection(self.cutpoints)

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B_cutpoints.append(points) 
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Q = self._inititalize_component_tree_weight()

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while Q:

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pair = Q.pop(0)

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if pair['type'] == 'component_vertex_pair': 
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B_index = pair['value'][0] 
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v = pair['value'][1] 
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size = len(self.bicomponents[B_index])  1; 
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all_cutpoints = self.bicomponents[B_index].intersection(self.cutpoints) 
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all_cutpoints.remove(v) 
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for cp in all_cutpoints: 
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if self.get_link_weight(B_index, cp) != 1: 
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size += self.num_vertices  self.get_link_weight(B_index, cp)  1 
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link_weight = size 
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self._verify_link_weight(B_index, v, link_weight)

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self.set_link_weight(B_index, v, link_weight)

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# update Q

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Q = self._find_unknown_weight_wrt_cutpoint(v, Q)

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if pair['type'] == 'vertex_component_pair': 
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size = 0

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B_index = pair['value'][0] 
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v = pair['value'][1] 
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shared_comp_indices = self._components_sharing_cutpoint(B_cutpoints, v)

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shared_comp_indices.remove(B_index) 
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for i in shared_comp_indices: 
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if self.get_link_weight(i, v) !=  1: 
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size += self.get_link_weight(i, v)

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link_weight = self.num_vertices  1  size 
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self._verify_link_weight(B_index, v, link_weight)

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self.set_link_weight(B_index, v, link_weight)

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# update Q

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Q = self._find_unknown_weight_wrt_component(B_index, Q)

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def _verify_link_weight(self, B_index, v, value): 
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""" If the old_value exist in self.Dv_B, then it must be equal to new value

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Otherwise, do nothing

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"""

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old_value = self.get_link_weight(B_index, v)

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if old_value != 1: # 1 is unknown 
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if old_value != value:

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print "BUGS FOUND in _verify_link_weight()" 
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sys.exit() 
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def _inititalize_component_tree_weight(self): 
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Q = [] 
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for i, comp in enumerate(self.bicomponents): 
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current_cutpoints = self.cutpoints.intersection(comp)

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if len(current_cutpoints) == 1: 
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Q.append({ 
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'type': 'component_vertex_pair', 
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'value': (i, list(current_cutpoints)[0]) # (B_i, cutpoint) = (ith component, the cutpoint name) 
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}) 
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for cp in current_cutpoints: 
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self.set_link_weight(i, cp, 1) 
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return Q

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def _find_unknown_weight_wrt_cutpoint(self, cutpoint, Q): 
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# Cutpoint v such that the weights of all but one of its links in T are already computed.

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num_of_uncomputed_weight = 0

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uncomputed_component_index = [] 
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for i, Dv_B_comp in enumerate(self.Dv_B): 
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if cutpoint in Dv_B_comp: 
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if Dv_B_comp[cutpoint] == 1: 
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num_of_uncomputed_weight += 1

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uncomputed_component_index.append(i) 
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if num_of_uncomputed_weight > 1: 
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break

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if num_of_uncomputed_weight == 1: 
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pair = { 
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'type': 'vertex_component_pair', 
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'value': (uncomputed_component_index.pop(), cutpoint)

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} 
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Q.append(pair) 
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return Q

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def _find_unknown_weight_wrt_component(self, comp_index, Q): 
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# Component B such that weights of all but one of its links in T are already computed.

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Dv_B_comp = self.Dv_B[comp_index]

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values = Dv_B_comp.values() 
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# Check if 1 value appear only 1 time

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flag = False

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minus_one_value = [x for x in values if x == 1] 
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if len(minus_one_value) == 1: 
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for cp, value in Dv_B_comp.iteritems(): 
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if value == 1: 
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pair = { 
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'type': 'component_vertex_pair', 
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'value': (comp_index, cp)

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} 
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Q.append(pair) 
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return Q

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def __str__(self): 
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return str(self.Dv_B) 
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