def main():
"""Examples: how to use VBP, AFG, MPS, LP and VPSolver"""
# Create instanceA:
instanceA = VBP([5180], [1120, 1250, 520, 1066, 1000, 1150],
[9, 5, 91, 18, 11, 64], verbose=False)
# Create instanceB from a .vbp file
instanceB = VBP.from_file("instance.vbp", verbose=False)
# Create an arc-flow graph for instanceA
afg = AFG(instanceA, verbose=False)
# Create .mps and .lp models for instanceA
mps_model = MPS(afg, verbose=False)
lp_model = LP(afg, verbose=False)
# Draw the arc-flow graph for instanceA (requires pygraphviz)
try:
afg.graph().draw("tmp/graph.svg")
except Exception as e:
print repr(e)
# Solve instanceA using bin/vpsolver (requires Gurobi)
try:
out, sol = VPSolver.vpsolver(instanceA, verbose=True)
except Exception as e:
print "Failed to call vpsolver"
print repr(e)
# Solve instanceA using any vpsolver script (i.e., any MIP solver):
# The scripts accept models with and without the underlying graphs.
# However, the graphs are required to extract the solution.
out, sol = VPSolver.script("vpsolver_glpk.sh", lp_model, afg, verbose=True)
try:
out, sol = VPSolver.script(
"vpsolver_gurobi.sh", mps_model, verbose=True
)
except Exception as e:
print repr(e)
# Solve an instance directly without creating AFG, MPS or LP objects:
out, sol = VPSolver.script("vpsolver_glpk.sh", instanceB, verbose=True)
# Print the solution:
obj, patterns = sol
print "Objective:", obj
print "Solution:", patterns
# Pretty-print the solution:
vbpsolver.print_solution(obj, patterns)
assert obj == 21 # check the solution objective value
