Constraints with For loop

Answered

Parijat Mitra

November 27, 2020 15:52

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Can I add or define a constraints inside a FOR loop. I am using python interface

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• Official comment

  

  Juan Orozco

  • Gurobi Staff

  November 27, 2020 17:05

  Dear Parijat,

  That's indeed possible. Please find below an assignment problem I implemented with the Gurobi-Python interface:

  import gurobipy as gp
  from gurobipy import GRB
  
  resources = ["r1", "r2", "r3"]
  jobs = ["j1", "j2", "j3"]
  costs = {("r1","j1"):1,("r1","j2"):2,("r1","j3"):3,
  ("r2","j1"):2,("r2","j2"):2,("r2","j3"):2,
  ("r3","j1"):3,("r3","j2"):2,("r3","j3"):1}
  
  model = gp.Model("assignment")
  
  assign = model.addVars(resources, jobs, vtype=GRB.BINARY, name="assign")
  
  #model.addConstrs((assign.sum(r,"*") == 1 for r in resources), name="supply")
  for r in resources:
      model.addConstr(assign.sum(r,"*") == 1, name=f"supply[{r}]")
  
  #model.addConstrs((assign.sum("*", j) == 1 for j in jobs), name="demand")
  for j in jobs:
      model.addConstr(assign.sum("*", j) == 1, name=f"demand[{j}]")
  
  model.setObjective(assign.prod(costs), GRB.MINIMIZE)
  
  model.optimize()

   

  I suggest you to check the functional code examples we provide in our website (please see here).
• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  June 23, 2025 03:04 Edited

  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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