Append a variable to a list

回答済み

Sanaa MARZOUG

2022年08月29日 20:22

• 
• 

hello,

I am trying to append a gurobi varible to a list with this code:

Prod_values = {}
obj_vars = []
Plants = range(7)
for l in range(7):
    for p in Demand:
        for d in Horizon:
            Prod_values = model.addVars(Plants,Demand,Horizon,lb = 0, vtype =GRB.INTEGER, name ='Prod_engrais')
            obj_vars.append(Prod_values[(l,p,d)])

but when i print obj_vars, it doesn't return the same values as Prod_values. Could you provide me with some help. 

Thank you for reading this post and helping me out!

0

• 正式なコメント

  

  Simranjit Kaur

  • Gurobi Staff

  2025年11月16日 23:29

  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.
• 

  Jaromił Najman

  • Gurobi Staff

  2022年08月30日 12:15

  Hi Sanaa,

  Please note that your example is not reproducible, because values for Demand and Horizon are missing.

  Moreover, you are adding Plants x Demand x Horizon variable in each loop iteration by using the addVars method. If you want to assign a value to a certain dictionary field, you have to access it via \(\texttt{Prod_values[l,p,d] = ...}\)

  What you are probably looking for is something like

  import gurobipy as gp
  from gurobipy import GRB
  
  model = gp.Model()
  
  Prod_values = {}
  obj_vars = []
  Plants = range(4)
  Demand = range(3)
  Horizon = range(2)
  for l in Plants:
      for p in Demand:
          for d in Horizon:
              Prod_values[l,p,d] = model.addVar(lb = 0, vtype =GRB.INTEGER, name ='Prod_engrais[%d,%d,%d]'%(l,p,d))
              obj_vars.append(Prod_values[(l,p,d)])
  model.update()
  print(Prod_values)
  print(obj_vars)

  Best regards, 
  Jaromił

  0

投稿コメントは受け付けていません。