Pyomo + Couenne: Infeasibility produces noisy warnings!

[sascha...@gmail.com]

Hi,

when using pyomo and couenne, infeasibility of the instance results in a warning, which is printed to the console.

This is a bit noisy and wasn't what i expected.

My usage looks to be conform to the documentation: create solver, create model, add vars, add constraints and run solver.opt(instance). The warning is printed before one could check the status.

A small code example:

from pyomo.environ import *

opt = SolverFactory('couenne')

m = ConcreteModel()

m.A = Var(range(10), domain=Boolean)

m.B = Var(range(10), domain=Boolean)

def c0_rule(m):

    return m.A[0] + m.B[0] >= 3

m.c0 = Constraint(rule=c0_rule)

results = opt.solve(m)

print('...printed after warning')

 

1. The usage is ok, right?

2. Is this intended?

3. If it is intended, is there any (non-ugly; e.g. filtering of stdout) workaround? It looks, that pyomo is to blame, so that there is nothing to do about setting couenne-parameters.

Thanks,

Sascha

[Gabriel Hackebeil]

If you pass “load_solutions=False” to the solve() method then the solution part of the results object will not be loaded into the model. You can do something like:

from pyomo.opt import TerminationCondition

...

results = opt.solve(model, load_solutions=False)

if results.solver.termination_condition == TerminationCondition.optimal:

model.solutions.load_from(results)

else:

…

Gabe

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[sascha...@gmail.com]

Thanks! That's exactly what i needed.

I searched the docs, but i think this method of calling is not mentioned at all. Maybe this should be added.

-

Sascha