Gurobi as a function

Answered

Akbar Rugova

October 29, 2023 13:26

Dear Gurobi Professional,

I currently have a problem regarding incorporation of gurobi as a function.

The intended purpose is that I can eventually extract the solution and plot it using plotly in a single script

The code:

def UPMSet(jobs,machines,workers,activities,oprttime,machining,moving,B):
    from gurobipy import GRB
    m = Model()
    x = {}
    for k in workers:
        for h in machines:
            for a in activities:
                for j in range (0, len(jobs)+1):
                    for i in machines:
                        for b in activities:
                            for l in jobs:
                                x[k,h,a,j,i,b,l] = m.addVar(vtype=GRB.BINARY,name='x_%s_%s_%s_%s_%s_%s_%s' % (k,h,a,j,i,b,l))

 

However, there's an error saying:

name 'Model' is not defined

Apparently the m = Model() is not defined. I recon there's a problem in the first 2 line of the code but Im not really sure.

I can normally run the gurobi code on its own but when it comes to include it as a function it fails me.

I'm quite new to gurobi and some of my explanation might be a wrong and a bit confusing but thats the broad idea.

Could you help me sort this problem out?

Thank you.

0

• 

  Riley Clement

  • Gurobi Staff

  October 30, 2023 02:35 Edited

  Hi Akbar,

  The issue here relates to programming in Python, in general, rather than being specific to Gurobi.  You can find a good explanation in the YouTube video: https://www.youtube.com/watch?v=CqvZ3vGoGs0

  So, "Model" is a thing which comes from the gurobipy package, so you need to tell Python this information.  You can achieve this with the following alternatives:

  from gurobipy import Model
  
  m = Model()

  import gurobipy
  
  m = gurobipy.Model()

  import gurobipy as gp
  
  m = gp.Model()

  Note that the last option is the preferred style.

  I also suggest moving your import statements to the top of your file, and taking advantage of our Model.addVars function:

  import gurobipy as gp
  from gurobipy import GRB
  
  def UPMSet(jobs,machines,workers,activities,oprttime,machining,moving,B):
      m = gp.Model()
      x = m.addVars(
          workers, machines, activities, len(jobs), machines, activities, jobs,
          vtype="B",
      )
      ...

  - Riley

   

   

   

  0

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