Variable not in model when setting objective

Answered

Hpone Myat Khine

September 19, 2021 04:40

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So I'm running a model - I successfully solved it using naive approach but I want to try and use a more general model form. However when running it I get the variable not in error for my set objective 

 

#Model set-up

m1 = Model('Nutrition')

#Create Variables

x_1 = m.addVars(N, name = 'fruits')

print(x_1)

#Set objective
m1.setObjective(quicksum(cost[i]*x_1[i] for i in range(N)), GRB.MINIMIZE)

#Add Constraints

m1.addConstrs(matrix_fruits[i,j]*x_1[j] for j in range(N)>= min_nutrition[i] for i in range(M))
m1.addConstrs(matrix_fruits[i,j]*x_1[j] for j in range(N)<= max_nutrition[i] for i in range(M))

# Print optimal solutions and optimal value
print('-------------------------------------')

for v in m.getVars():
print(v.VarName, v.x1)

print('Obj:', m1.objVal)

is the code 

N in this case represents the 5 variables I have 

0

• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  June 23, 2025 02:47 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

  September 20, 2021 08:08

  Hi,

  The line where you add the variable is adding them to a wrong model \(\texttt{m}\) instead of your Nutrition model \(\texttt{m1}\). The addVars line should read

  x_1 = m1.addVars(N, name = 'fruits')

  Best regards,
  Jaromił

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