Writing a Constraint using quicksum

Answered

Abhishek Bajpai

• September 15, 2022 10:14

Hi team,

I am new to Gurobi.

I am using it for some cost optimisation.

Can someone guide me with writing this constraint?

i & t are the values inside my Variable list.

0

• 

  Jaromił Najman

  Gurobi Staff

  • September 15, 2022 10:55
  • Edited

  One way would be

  import gurobipy as gp
  from gurobipy import GRB
  
  T = list(range(0,10))
  I = list(range(0,10))
  
  m = gp.Model()
  
  N = m.addVars(I,T)
  
  constraints = m.addConstrs((gp.quicksum(N[i,t] for t in T) == 1 for i in I), name="constraint")

   

  Here are a few good resources to get you started with nested summations:

  • Python I: Introduction to Modeling with Python - Gurobi. This is your best place to start.  It includes a video tutorial and examples with jupyter notebooks for you to follow.  It also includes an example of using nested summations.
  • netflow.py: This is a Gurobi example of how to do nested summations in two different ways: (a) using quicksum and (b) using tupledict.sum()
  • quicksum() documentation

  Best regards, 
  Jaromił

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