TypeError: float() argument must be a string or a real number, not 'gurobipy.LinExpr'

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Wenbo Ma

June 09, 2024 19:29

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Hello, I am trying to add constraints but encounter an error that I couldn't figure out how to get around. 

m.addConstrs((T @ f_a + M_a * (1 - z_hat[k]) >= eta.loc[k, :].values for k in K))

In my code, T is a numpy.ndarray (elements are 0 or 1 constants), f_a is a gurobi MVar object, M_a is a numpy.ndarry (elements are constants), and z_hat[k] is a gurobi variable. I can see the error comes from adding the T @ f_a and the M_a * (1 - z_hat[k]) together. Running T @ f_a and M_a * (1 - z_hat[k]) separately did not produce an error. It only appears when adding them together.

TypeError: float() argument must be a string or a real number, not 'gurobipy.LinExpr'

Thanks for the help.

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  David Torres Sanchez

  • Gurobi Staff

  June 14, 2024 10:59

  Have you tried making \(\texttt{z_hat}\) also an MVar?

  Cheers, 
  David

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