Writing a Constraint using quicksum

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Abhishek Bajpai

2022年09月15日 10:14

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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.

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  Simranjit Kaur

  • Gurobi Staff

  2025年11月16日 23:28

  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 try Gurobot, our chatbot interface offering instant, expert-level support.
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  Jaromił Najman

  • Gurobi Staff

  2022年09月15日 10:55 編集済み

  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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