Need a specific format of decision variable i.e. <gurobi.Var C0> instead of <gurobi.Var *Awaiting Model Update*> when I iterate over loop.? any idea how to get this.? I need this format to use specific package of neural network.

Answered

Vigneshwar Pesaru

June 22, 2023 04:20

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In-order to get this format :

[<gurobi.Var C0>,

<gurobi.Var C1>,

<gurobi.Var C2>,

...

...]

 

I put in the loop as below..

count = 0

input_vars = []

while count <= 30:

    input_vars.append(opt_model.addVar(0, 300, vtype=grb.GRB.CONTINUOUS))

    count+=1

But still I am getting the output as :

[<gurobi.Var *Awaiting Model Update*>,

<gurobi.Var *Awaiting Model Update*>,

<gurobi.Var *Awaiting Model Update*>,

<gurobi.Var *Awaiting Model Update*>, <gurobi.Var *Awaiting Model Update*>,

0

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  Simranjit Kaur

  • Gurobi Staff

  June 22, 2023 05:08 Edited

  Hi Vigneshwar,

  Model modification in Gurobi is performed in a lazy fashion, meaning that the modifications don't affect the model immediately. Instead, they are queued and are applied later, with the calls to model.update(), model.optimize() or model.write() methods.

  To access a variable attribute immediately after adding the variable to the model, please execute the model.update() method before accessing the variables.

  You can read more about Gurobi's lazy update approach here.

  Best regards,

  Simran

  1

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