Constraint with for loop

Answered

Rayan SAAD

July 03, 2023 14:33

Hello,

I have a lillte probleme and would appreciate your help,

I created a variable X[i,j]

I want to add constraints on X dependently of i,

for example if i equal to 2,3,4 i have a constraint

and if i equal to 1,5,6 i have an other one

Thank you for your help

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Official comment
Simranjit Kaur

Gurobi Staff

November 13, 2026 01:41
This post is more than two 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 try Gurobot, our chatbot interface offering instant, expert-level support.
Chung-Kyun Han

Gurobi Staff

July 05, 2023 07:10
Hi Rayan,

Thank you for reaching us again.

You can write concise code when you refer to our 'Python Dictionary Example' page.
And, specifically, you can resolve your issue with 'tuplelist class'.

The following is an arbitrary example utilizing the tuplelist class.
```
import gurobipy as gp

l = gp.tuplelist([(i, j) for i in range(10) for j in range(10)])

m = gp.Model()
x = m.addVars(l, name="x")
m.update()

m.addConstr(x[0, 0] <= gp.quicksum(i + j * x[i, j] for i, j in l.select([2, 3, 5], '*')))
m.addConstr(x[1, 1] <= gp.quicksum(i + j * x[i, j] for i, j in l.select([1, 5, 6], '*')))
```
Feel free to leave comments if you have any further questions.

Best regards,
Chung-Kyun Han
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