Help with python callback -- adding callback on different line than optimize()

Answered

Austin Buchanan

• March 05, 2021 22:37
• Edited

I am using a cut callback in some python code. Normally, I would follow the example set in the tsp.py code, which does the following:

m.optimize(subtourelim)

You can see that it passes the callback "subtourelim" to optimize(). For code organization reasons, I would like to separate these two things, similar to the tsp.cpp example:

    // Set callback function

    subtourelim cb = subtourelim(vars, n);

    model.setCallback(&cb);

    // Optimize model

    model.optimize();

Can this be done in python? 

0

• 

  Eli Towle

  Gurobi Staff

  • March 05, 2021 22:55

  The only way to set a callback function in the Python API is by passing the function object as an argument to Model.optimize().

  The default argument of Model.optimize() is \( \texttt{None} \), which tells Gurobi there is no callback function. So you could do something like this:

  m._cb = subtourelim  # or None
  m.optimize(m._cb)

  1

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