PULP - How to get the CPLEX solver status instead of the LpStatus stauts?

Question

I'm using the CPLEX solver via PULP in Python. When I solve a problem with time limit, CPLEX prints to the screen the code 107 which means "Time limit exceeded, but integer solution exists". However, if I print the status of pulp.LpStatus[problem.status] what I get back is the value 1 which according to pulp's documentation means an optimal solution has been found, which is actually wrong.

How can I access the CPLEX status codes instead of PULP's?

Answer 1

You can directly access CPLEX status code and status string. Consider the following example:

>>> import pulp 
>>> prob = pulp.LpProblem("example", pulp.LpMinimize)
>>> x = pulp.LpVariable('x', lowBound=0, upBound=1)
>>> prob+= x <= -1

• Example 1 - Time limit exceeded

  >>> solver = pulp.CPLEX_PY(msg=0, timeLimit=0)
  >>> prob.setSolver(solver)
  >>> prob.solve()
  -3
  >>> solver.solverModel.solution.get_status()
  108
  >>> solver.solverModel.solution.get_status_string()
  'time limit exceeded, no integer solution'
  

• Example 2 - Infeasible

  >>> solver = pulp.CPLEX_PY(msg=0)
  >>> prob.setSolver(solver)
  >>> prob.solve()
  -1
  >>> solver.solverModel.solution.get_status()
  103
  >>> solver.solverModel.solution.get_status_string()
  'integer infeasible'