Generate multidict using for loop in Gurobi

Answered

John Raphy Karippery

October 10, 2021 13:35

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I would like to generate multidict in Gurobi.

inputs:

from gurobipy import *

number_of_vehicles = 2 
vehicles_origin = [4, 6]
vehicles_destination = [3, 0]
total_time_vehicle = [35, 27]

I would like to add this input to multidict in Gurobi using for loop.

output:

truck, starting_node, destination_nodes, time = 
multidict({0:[4,3,(35)],1:[6,0,(27)]})

0

• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  June 23, 2025 02:46 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?.
• 

  Jaromił Najman

  • Gurobi Staff

  October 11, 2021 07:49

  The multidict function generates multiple dictionaries out of a single larger dictionary data. You can construct the dictionaries via \(\texttt{for}\)-loops

  from gurobipy import *
  
  number_of_vehicles = 2 
  vehicles_origin = [4, 6]
  vehicles_destination = [3, 0]
  total_time_vehicle = [35, 27]
  
  truck = [i for i in range(number_of_vehicles)]
  starting_node = {}
  destination_nodes = {}
  time = {}
  for i in truck:
    starting_node[i] = vehicles_origin[i]
    destination_nodes[i] = vehicles_destination[i]
    time[i] = total_time_vehicle[i]

  If you insist on using the multidict function, you can pre-construct the larger dictionary

  multi = {}
  for i in range(number_of_vehicles):
    l = [vehicles_origin[i],vehicles_destination[i],total_time_vehicle[i]]
    multi[i] = l
  
  truck, starting_node, destination_nodes, time = multidict(multi)

  Best regards,
  Jaromił

   

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