addGenConstrMax:'gurobipy.LinExpr' object has no attribute '__cindex__'

Answered

Yutong Zhang

November 27, 2022 09:15

I was trying to add a constraint as following:

for i in demand_list:
    maxVarsList = [data1.loc[i,j]*x[j] for j in truck_list]
    m.addGenConstrMax(sum(z[i,j] for j in truck_list), maxVarsList)

note: x[j] is a binary decision variable, z[i,j] is a decision variable, data1.loc[i,j] is a given variable.

AttributeError: 'gurobipy.LinExpr' object has no attribute '__cindex__'

How to add this max constraint correctly?

Related to

• General Constraints

0

• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  November 13, 2026 01:52

  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.
• 

  Jonasz Staszek

  • Community Moderator

  November 28, 2022 07:08

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  • 
  • 

  Dear Yutong,

  could you please share a minimal reproducible example of the code which throws the error you mention?

  Best regards
  Jonasz

  0
• 

  Jaromił Najman

  • Gurobi Staff

  November 28, 2022 09:37

  Dear Yutong,

  On top of providing a minimal reproducible example as noted by Jonasz, please note that the addGenConstrMax method does not accept an expression as its input. You have to provide a single optimization variable as first argument. Thus, you have to introduce an auxiliary variable \(aux\) and add the auxiliary equality constraint \(aux = \sum z_{ij}\), \(aux = \max(\dots)\).

  Best regards, 
  Jaromił

  0

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