Changing parameter lists within the optimization

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Tristan Messmer

2020年01月14日 21:37

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Hey guys,

I'm currently writing my Bachelor's Thesis about two models concerning optimal empty container management. I've ran into a problem that I haven't been able to solve for days. Here's the problem:

There are 21 storage yards that the model can consider to deliver empty containers to 50 shippers. There's a parameter p that tells the model how many storage yards out of the 21 it has to locate. For each shipper there is a list of the storage yards that ranks them according to distance to the yard (closest 1st, furthest 21st). Now I need the model to re-rank this list for each shipper according to p.

Example:

Original List "Shipper4": {1: "Yard3", 2: "Yard5", 3: "Yard1", 4: "Yard2", 5: "Yard4"}

New List if p = 3 and the model just locates Yards 1, 2, and 3 --> {1: "Yard3", 2: "Yard1", 3: "Yard2"}

 

How do I get this result? There is a binary variable that is 1 if a yard is located and 0 if it is not.

 

Thanks in advance

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  Simranjit Kaur

  • Gurobi Staff

  2024年12月06日 00:50

  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?.
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  Silke Horn

  • Gurobi Staff

  2020年01月22日 10:05

  Hi Tristan,

  I guess we would need more information in order to help you. Here are just some questions that come to my mind:

  What are the (relevant) decision variables in your model?

  When is the value of p determined? Is it a decision variable or a constant whose value you know when the model is built?

  And when are the orders for the shippers determined? Are they inputs for your model?

  Best regards,
  Silke

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