Writing a Constraint using quicksum

Answered

Maxim Vodyan

March 27, 2023 11:15 Edited

Hi team, I am new to Gurobi.

Can someone guide me with writing this constraint?

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3 comments

David Torres Sanchez

Gurobi Staff

March 27, 2023 11:19
Hi Maxim,

Please provide a Minimal Reproducible Example (MRE) showing what you have already done and the error you are observing.

Cheers,
David
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Maxim Vodyan

March 27, 2023 11:55
It takes a lot of time to build an MRE. C is an array of options that are predefined. x and y are boolean variables. I used this constraint:
```
m.addConstrs((gp.quicksum(c[i][j] * x[(i, j)] for i in range(N)) <= c[k][j] * y[k] for k in range(N) for j in range(M)), name="Profit")
```
Does it match this?

I get an error: Unable to retrieve attribute 'ObjVal'. Did you mean: 'ObjNVal', when trying to take the optimum value. I think that the solver cannot find the optimal solution, given the constraint.
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David Torres Sanchez

Gurobi Staff

March 27, 2023 12:04
Hi Maxim,

The constraint looks like it matches.
The error you are getting may indicate that you need to call \(\texttt{m.optimize()}\) before trying to extract the solution.

Cheers,
David
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