Save Julia Gurobi model and load and run with different datainputs

Ongoing

Katinka Klepsch

October 28, 2022 09:37

• 
• 
• 

I have a Gurobi model in the attached format.

My question is probably fairly simple. I am trying to expand the model and with stochastic data inputs. So I want to run the model with different data inputs (the data inputs being eg. missed_bags). 
My question is - Is it possible to save the model and then load the model in another Julia file where I can run the model with different data inputs. 

```
For iter in iterations
    x_result = Run Gurobi_model(missed_bags).  # get assignment
    for sim in simulations
        data = data + std*rand()
        # compute values based on assignment result
        # some stuff happens here
    end
    # Update missed_bags matrix based on simulation results

end

```

My model is made with the following syntax (this I just and extract)

```

Gurobi_model = Model(Gurobi.Optimizer);

variable(Gurobi_model, x[1:Fa, 1:I], Bin); # Binary variable: 1 if arriving flight fa is assigned to in-feed i
@variable(Gurobi_model, y[1:T], Bin) 

# objective function: Minimise the number of missed bags
@objective(Gurobi_model, Min, sum(x[fa,i]*missed_bags[fa,i] for i=1:I, fa=1:Fa) + sum(500*y[t] for t = 1:T)+ sum(0.5*x[fa,i] for i in [2,3,5,6], fa=1:Fa))

@constraint(Gurobi_model, [fa = 1:Fa], (sum(x[fa,i] for i = 1:I) == 1))

# constraints that ensures to add penalty if loading capacity is violated 

# Solution
optimize!(Gurobi_model)

# print statement
....

```

I hope you guys can help!

0

• 

  Jonasz Staszek

  • Community Moderator

  October 28, 2022 13:32

  • 
  • 
  • 

  Hi Katinka,

  I'm no expert in Julia, but perhaps it is possible to export a module (in particular I mean to export the methods which you use to generate the model, then load them someplace else and use them with new data)?

  Best regards
  Jonasz

  1
• 

  Katinka Klepsch

  October 30, 2022 17:20

  • 
  • 
  • 

  Thanks! That helps.

  However I cannot use the variable (eg x) in another fil when I try to use x. And I when I try to return x in my function in the module, it just returns the model instead. Do you know why? :-)

  include("01initial_model_module.jl")

  using JuMP

  using Gurobi

  
  

  using .model_module_test

  path_to_data = "data_final_v1.jl" # path to data

  model = deterministic_model_test(path_to_data)

  optimize!(model)

  if termination_status(model) == MOI.OPTIMAL

        xres=value.(x) ---> ERROR

  end

   

   

   

  0

Please sign in to leave a comment.