Gurobi for Python Declaring Variables Using Distinct Indices

Answered

Nic Woyak

• September 25, 2019 21:21

Suppose I have some binary variable X indexed by set S twice over where properly speaking X should only be indexed by distinct pairs. 

I am familiar with AMPL where this declaration would be be:

var X{s in S, ss in S: s<>ss} binary;

I want to duplicate the bold part of the above declaration in my Python declaration below, so I would have to add on to or modify it in some way:

X = m.addVars(S, S, vtype=GRB.BINARY)

How do I do this?

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• Official comment

  

  Simranjit Kaur

  Gurobi Staff

  • December 06, 2024 00:53

  This post is more than three years old. Some information may not be up to date. For current information, please check the Gurobi Documentation or Knowledge Base. If you need more help, please create a new post in the community forum. Or why not try our AI Gurobot?.
• 

  Greg Glockner

  Gurobi Staff

  • September 26, 2019 00:10

  Try creating the index as a generator expression:

  X = m.addVars(((s, ss) for s in S for ss in S if s != ss), vtype=GRB.BINARY)

   

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