Constraints with For loop

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Parijat Mitra

2020年11月27日 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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  Juan Orozco

  • Gurobi Staff

  2020年11月27日 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).
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  Simranjit Kaur

  • Gurobi Staff

  2025年06月23日 03:04 編集済み

  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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