Problem formulation for to satisfy the demand for a list of products

Answered

Krzysztof Suwada

August 20, 2024 14:04

• 
• 
• 

I would like to introduce a penalty connected with the number of parcels sent from one location to another.

Something like: 
- if the number of parcels sent is < 15 then the penalty is 0
- [15, 20) penalty is 10
- [20, 30) penalty is 50
- [30, infinity) penalty is 1000000

I have a variable the counts number of packages sent from one location to another count_parcels[(loc_from, loc_to)] how to create the penalty?

0

• Official comment

  

  Juan Orozco

  • Gurobi Staff

  August 20, 2024 19:24

  You can use the method model.setPWLObj(), so I suggest to read the associated documentation, as well as the section Objectives of our reference manual.
• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  November 13, 2026 01:21

  This post is more than two 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.
• 

  Krzysztof Suwada

  August 22, 2024 10:11 Edited

  • 
  • 
  • 

  Ok, and what if I want it to be a part of a variable?
  something like this code

  for loc_a in locations:
          for loc_b in locations:
              if loc_a != loc_b:
                  m.addConstr(total_value[loc_a, loc_b] == quicksum(x[loc_a, loc_b, p]*price[p] for p in products))
                 if total_value[loc_a, loc_b] < 1500 and total_value[loc_a, loc_b] > 1000:
                       m.addConstr(value_penalty[loc_a, loc_b] = 1500 - total_value[loc_a, loc_b])
                 else:
                      m.addConstr(value_penalty[loc_a, loc_b] = 2*(1500 - total_value[loc_a, loc_b])) 

   

  0
• 

  Krzysztof Suwada

  August 22, 2024 10:16

  • 
  • 
  • 

  And then I want to sum-up all the penalties and add it to a objective function.

   

  0
• 

  Jonasz Staszek

  • Community Moderator

  August 30, 2024 12:35 Edited

  • 
  • 
  • 

  Hi Krzysztof,

  I would suggest that you proceed in the way suggested by Juan.

  Perhaps the following code snippet will be an inspiration for you:

  for loc_a in locations:
          for loc_b in locations:
              if loc_a != loc_b:
                  m.setPWLObj(total_value[loc_a, loc_b], [0, 15, 20, 30], [0, 10, 50, 1000000])

  It should generally do everything you are after: define a piecewise-linear penalty for your variables and include them in your objective function.

  Hope this helps.

  Best regards
  Jonasz

  0

Post is closed for comments.