promblems in pyomo

[jinyu yue]

Something wrong with my code, and gurobi with pyomo cant solve the problem. It seems wrong at presolve progress and I dont know how to make it right.

Optimize a model with 50163 rows, 967 columns and 4569 nonzeros
Model fingerprint: 0x3c53ad90
Variable types: 751 continuous, 216 integer (216 binary)
Coefficient statistics:
  Matrix range     [2e-01, 1e+02]
  Objective range  [1e+00, 1e+00]
  Bounds range     [1e+00, 1e+03]
  RHS range        [5e-02, 1e+02]
Presolve removed 48419 rows and 199 columns
Presolve time: 0.00s

Explored 0 nodes (0 simplex iterations) in 0.00 seconds (0.00 work units)
Thread count was 1 (of 16 available processors)

Solution count 0

Model is infeasible
Best objective -, best bound -, gap -
WARNING: Loading a SolverResults object with a warning status into
model.name="unknown";
    - termination condition: infeasible
    - message from solver: Model was proven to be infeasible.

[Andres Ramos]

For solving infeasibilities we write the lp file and then we use gurobipy with the iis option to detect the constraint or variable that is causing the infeasibility.

Alternatively, we can send me the lp file and I can try to do it

Regards

Andrés

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De: 'jinyu yue' via Pyomo Forum <pyomo...@googlegroups.com>
Enviado: martes, 25 de marzo de 2025 14:11
Para: Pyomo Forum <pyomo...@googlegroups.com>
Asunto: promblems in pyomo

 

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[Andres Ramos]

Yo can use this file as starting point

Andrés

from gurobipy import *
# import gurobi_modelanalyzer as gma

m=read('file.lp')
m.printStats()
# m.setParam('getA()',)
m.setParam('Method'   ,2)
m.setParam('BarHomogeneous'   ,1)
# m.setParam('Crossover',0)
# m.setParam('OutputFlag', 1)
# m.setParam('LogToConsole', 1)
# m.setParam('NumericFocus', 3)
# m.setParam('IISMethod', 0)
# m.setParam('BarHomogeneous', 1)
# m.setParam('FeasRelaxS', 0)
# m.feasRelaxS(2, False, False, True)
# # m.write('p2.lp')
# m=m.presolve()
# m.write('caso209h_ps.lp')
m.optimize()

# m.printQuality()
# print(m.KappaExact)
# gma.kappa_explain(m)

m.computeIIS()
m.write('pp.ilp')

# Print out the IIS constraints and variables
# print('\nThe following constraints and variables are in the IIS:')
# for c in m.getConstrs():
#     if c.IISConstr:
#         print(f'\t{c.constrname}: {m.getRow(c)} {c.Sense} {c.RHS}')
# for v in m.getVars():
#     if v.IISLB:
#         print(f'\t{v.varname} ≥ {v.LB}')
#     if v.IISUB:
#         print(f'\t{v.varname} ≤ {v.UB}')

# m.getVarByName('vX(Algeciras_Madrid)').X

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De: 'jinyu yue' via Pyomo Forum <pyomo...@googlegroups.com>
Enviado: martes, 25 de marzo de 2025 14:11
Para: Pyomo Forum <pyomo...@googlegroups.com>
Asunto: promblems in pyomo

 

[Siirola, John]

Additionally, there are some utilities in Pyomo for diagnosing infeasibilities, including :

• A generic interface to Gurobi/Xpress/Cplex’s IIS routines (see https://pyomo.readthedocs.io/en/6.9.1/explanation/analysis/iis.html)
• An implementation of a Minimal Intractable System finder (see https://pyomo.readthedocs.io/en/6.9.1/explanation/analysis/iis.html)
• It is sometimes informative to add slack variables to every constraint and resolve as a constraint satisfaction problem.  There is a transformation that can automate this process (available from TransformationFactory('core.add_slack_variables'), implemented here: https://pyomo.readthedocs.io/en/6.9.1/api/pyomo.core.plugins.transform.add_slack_vars.AddSlackVariables.html).

 

Best,

John

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[.]

Thank you for the program, I use it to check the lp file. But I can't understand the output, because the constraint and bounds aren't what I write in my main file, what are they and what can I do now.  Meanwhile the lp flie is also strange.

T - T

------------------ 原始邮件 ------------------

发件人: "pyomo-forum" <arg...@gmail.com>;

发送时间: 2025年3月25日(星期二) 晚上9:43

收件人: "Pyomo Forum"<pyomo...@googlegroups.com>;

主题: RE: promblems in pyomo

[.]

Thank you for the answer, I use IIS to check lp file, but the bounds and constraints aren't what in my main file. What's the problem? 

W-W

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发送时间: 2025年3月26日(星期三) 凌晨0:35

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主题: RE: [EXTERNAL] RE: promblems in pyomo

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[Andres Ramos]

I don't understand your answer but if you want the lp file to use the same symbols you use in pyomo you must use this option

io_options={'symbolic_solver_labels': True}

when calling ModelName.write function

Regards

Andrés

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De: '.' via Pyomo Forum <pyomo...@googlegroups.com>
Enviado: viernes, 28 de marzo de 2025 4:05
Para: pyomo-forum <pyomo...@googlegroups.com>
Asunto: 回复：RE: [EXTERNAL] RE: promblems in pyomo

 

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[.]

thanks! The problem can be solved, but when the gap is close to 17%, the bound and gap change at a low speed, how to solve it.(main2.py is the project)

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发送时间: 2025年3月28日(星期五) 下午2:26

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主题: RE: 回复：RE: [EXTERNAL] RE: promblems in pyomo

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