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July 9, 2017 01:20
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Augment your Graph with an Augmenting Path
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def augment(augmentingPath, H): | |
augmentingPath = list(augmentingPath) | |
H_as_dict = digraph_to_dict(H) | |
new_nodes = frozenset({}) | |
new_arcs = frozenset({}) | |
visited_nodes = frozenset({}) | |
visited_arcs = frozenset({}) | |
bottleneck_residualCapacity = min( augmentingPath, key=lambda a: a.datum.residualCapacity ).datum.residualCapacity | |
for x in augmentingPath: | |
from_node_uid = x.fromNode.uid if x.datum.action == 'push' else x.toNode.uid | |
to_node_uid = x.toNode.uid if x.datum.action == 'push' else x.fromNode.uid | |
from_node = find_node_by_uid( from_node_uid, H ) | |
to_node = find_node_by_uid( to_node_uid, H ) | |
load = bottleneck_residualCapacity if x.datum.action == 'push' else -bottleneck_residualCapacity | |
for a in H_as_dict[from_node]: | |
if(a.toNode == to_node): | |
test_sum = a.datum.flow + load | |
new_flow = a.datum.flow | |
new_from_node_flow_out = a.fromNode.datum.flowOut | |
new_to_node_flow_in = a.toNode.datum.flowIn | |
new_from_look = {n for n in new_nodes if (n.uid == a.fromNode.uid)} | |
new_to_look = {n for n in new_nodes if (n.uid == a.toNode.uid) } | |
prev_from_node = new_from_look.pop() if (len(new_from_look)>0) else a.fromNode | |
prev_to_node = new_to_look.pop() if (len(new_to_look)>0) else a.toNode | |
new_nodes = new_nodes.difference(frozenset({prev_from_node})) | |
new_nodes = new_nodes.difference(frozenset({prev_to_node})) | |
if(test_sum > a.datum.capacity): | |
new_flow = a.datum.capacity | |
new_from_node_flow_out = prev_from_node.datum.flowOut - a.datum.flow + a.datum.capacity | |
new_to_node_flow_in = prev_to_node.datum.flowIn - a.datum.flow + a.datum.capacity | |
load = test_sum - a.datum.capacity | |
elif(test_sum < 0.0): | |
new_flow = 0.0 | |
new_from_node_flow_out = prev_from_node.datum.flowOut - a.datum.flow | |
new_to_node_flow_in = prev_to_node.datum.flowIn - a.datum.flow | |
load = test_sum | |
else: | |
new_flow = test_sum | |
new_from_node_flow_out = prev_from_node.datum.flowOut - a.datum.flow + new_flow | |
new_to_node_flow_in = prev_to_node.datum.flowIn - a.datum.flow + new_flow | |
load = 0.0 | |
new_from_node_flow_out = round(new_from_node_flow_out, TOL) | |
new_to_node_flow_in = round(new_to_node_flow_in, TOL) | |
new_flow = round(new_flow, TOL) | |
new_from_node = Node(prev_from_node.uid, FlowNodeDatum(prev_from_node.datum.flowIn, new_from_node_flow_out)) | |
new_to_node = Node(prev_to_node.uid, FlowNodeDatum(new_to_node_flow_in, prev_to_node.datum.flowOut)) | |
new_arc = Arc(new_from_node, new_to_node, FlowArcDatum(a.datum.capacity, new_flow)) | |
visited_nodes = visited_nodes.union(frozenset({a.fromNode,a.toNode})) | |
visited_arcs = visited_arcs.union(frozenset({a})) | |
new_nodes = new_nodes.union(frozenset({new_from_node, new_to_node})) | |
new_arcs = new_arcs.union(frozenset({new_arc})) | |
not_visited_nodes = H.setOfNodes.difference(visited_nodes) | |
not_visited_arcs = H.setOfArcs.difference(visited_arcs) | |
full_new_nodes = new_nodes.union(not_visited_nodes) | |
full_new_arcs = new_arcs.union(not_visited_arcs) | |
G = DiGraph(full_new_nodes, full_new_arcs) | |
full_new_arcs_update = frozenset([]) | |
for a in full_new_arcs: | |
new_from_node = a.fromNode | |
new_to_node = a.toNode | |
new_from_node = find_node_by_uid( a.fromNode.uid, G ) | |
new_to_node = find_node_by_uid( a.toNode.uid, G ) | |
full_new_arcs_update = full_new_arcs_update.union( {Arc(new_from_node, new_to_node, FlowArcDatum(a.datum.capacity, a.datum.flow))} ) | |
G = DiGraph(full_new_nodes, full_new_arcs_update) | |
return G |
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