g.add_node(2, pos='"2,0!"', demand=0)
g.add_node(4, pos='"4,2!"', demand=0)
g.add_node(6, pos='"6,4!"', demand=0)
g.add_node(5, pos='"6,0!"', demand=0)
g.add_node(7, pos='"8,2!"', demand=-4, label='(1, -4)')
g.add_edge(1, 3, cost=0, capacity=2, label='(0, 2)')
g.add_edge(1, 2, cost=0, capacity=2, label='(0, 2)')
g.add_edge(3, 4, cost=1, capacity=1, label='(1, 1)')
g.add_edge(3, 6, cost=2, capacity=2, label='(2, 2)')
g.add_edge(2, 4, cost=3, capacity=1, label='(3, 1)')
g.add_edge(2, 5, cost=5, capacity=1, label='(5, 1)')
g.add_edge(4, 6, cost=1, capacity=3, label='(1, 3)')
g.add_edge(4, 7, cost=4, capacity=2, label='(4, 2)')
g.add_edge(4, 5, cost=1, capacity=1, label='(3, 1)')
g.add_edge(6, 7, cost=0, capacity=2, label='(0, 2)')
g.add_edge(5, 7, cost=0, capacity=2, label='(0, 2)')
g.set_display_mode('pygame')
g.display()
# g.cycle_canceling('pygame')
g.min_cost_flow(algo='cycle_canceling')
# g.max_flow(1, 7)
nl = list(int(n) for n in g.get_node_list())
nl.sort()
for n in nl:
for m in nl:
if g.check_edge(n, m):
print(n, m, g.get_edge_attr(n, m, 'flow'))
T._incumbent_value = sum(IS)
print 'Heuristic solution value: ', T._incumbent_value
T.VARIABLES = []
T.CONSTRAINTS = []
T.OBJ = {}
T.RHS = {}
T.MAT = {}
T.branch_on_fractional = True
T.branch_strategy = b_rule
for i in nodes:
T.VARIABLES.append(i)
T.OBJ[i] = 1
for j in nodes:
if G.check_edge(i, j):
constraint_label = 'C_' + str(i) + '_' + str(j)
T.CONSTRAINTS.append(constraint_label)
for k in nodes:
T.MAT.update([((constraint_label, k), 0)
for k in nodes])
T.MAT[(constraint_label, i)] = 1
T.MAT[(constraint_label, j)] = 1
T.RHS[constraint_label] = 1
opt, optval, node_count = T.BranchAndBound()
for i in opt:
if opt[i] >= 0.5:
G.set_node_attr(i, 'style', 'filled')
G.set_node_attr(i, 'fillcolor', 'red')
g.add_node(2,pos='"2,0!"', demand=0)
g.add_node(4,pos='"4,2!"', demand=0)
g.add_node(6,pos='"6,4!"', demand=0)
g.add_node(5,pos='"6,0!"', demand=0)
g.add_node(7,pos='"8,2!"', demand=-4, label='(1, -4)')
g.add_edge(1, 3, cost=0, capacity=2, label='(0, 2)')
g.add_edge(1, 2, cost=0, capacity=2, label='(0, 2)')
g.add_edge(3, 4, cost=1, capacity=1, label='(1, 1)')
g.add_edge(3, 6, cost=2, capacity=2, label='(2, 2)')
g.add_edge(2, 4, cost=3, capacity=1, label='(3, 1)')
g.add_edge(2, 5, cost=5, capacity=1, label='(5, 1)')
g.add_edge(4, 6, cost=1, capacity=3, label='(1, 3)')
g.add_edge(4, 7, cost=4, capacity=2, label='(4, 2)')
g.add_edge(4, 5, cost=1, capacity=1, label='(3, 1)')
g.add_edge(6, 7, cost=0, capacity=2, label='(0, 2)')
g.add_edge(5, 7, cost=0, capacity=2, label='(0, 2)')
g.set_display_mode('pygame')
g.display()
# g.cycle_canceling('pygame')
g.min_cost_flow(algo='cycle_canceling')
# g.max_flow(1, 7)
nl = list(int(n) for n in g.get_node_list())
nl.sort()
for n in nl:
for m in nl:
if g.check_edge(n, m):
print n, m, g.get_edge_attr(n, m, 'flow')