modelling error

回答済み

Ege ö

2023年12月02日 10:47

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Hi,

I have an error for the below code which is written in python gurobi.I tried to add Constrs or different method but couldn't find the correction method. What do you suggest to get rid of this error?

Thank you in advance

F = m.addConstr( (R[month]/2 for month in months) == gp.quicksum(y[skill, month]*b[skill, month] for skill in skills for month in months), name ="R")

 

TypeError: unsupported operand type(s) for -: 'gurobipy.QuadExpr' and 'generator'

関連

• KeyError

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• 正式なコメント

  

  Simranjit Kaur

  • Gurobi Staff

  2026年11月13日 01:33

  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.
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  Simranjit Kaur

  • Gurobi Staff

  2023年12月03日 23:58 編集済み

  Hi,

  Are you trying to model 

  \[\sum_{m \in months} R_m/2 = \sum_{s \in skills, m \in months}y_{s,m}b_{s,m}\]
  or
  \[R_m/2 = \sum_{s \in skills}y_{s,m}b_{s,m} \qquad \forall \  m \in months \ ?\]

  Option 1 can be modelled as:

  F = m.addConstr( gp.quicksum(R[month]/2 for month in months) == gp.quicksum(y[skill, month]*b[skill, month] for skill in skills for month in months), name ="R")

  Option 2 can be modelled as:

  F = m.addConstrs( (R[month]/2 == gp.quicksum(y[skill, month]*b[skill, month] for skill in skills)  for month in months), name="R")

  I hope this helps.

   

  Best regards,

  Simran

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  Ege ö

  2023年12月09日 09:03

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  I was trying to write 2nd funtion, now it works, thank you for your support Simranjit :)

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  Ege ö

  2023年12月09日 12:20 編集済み

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  Hi Simranjit,

  I would be very happy if you make some comment s about below error too:

  Total_rev = m.addVars(months, vtype=GRB.CONTINUOUS, name="totalrevenue")
  Total_revenue= m.addConstr( (Total_rev[month] for month in months) == gp.quicksum( p[skill,product,month]*r[product]*x[skill, month] + k[skill,product,month]*r[product]*y[skill, month] for skill in skills for month in months for product in products), name= "rev") 

  KeyError: (1, 1, 1)

  
   

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  Simranjit Kaur

  • Gurobi Staff

  2023年12月11日 03:09

  Hi Ege,

  A KeyError is raised when you try to access an element before it is created. Please check if p[1,1,1] and k[1,1,1] exist.

  Also, please consider re-writing the Total_revenue constraint. In its current form, it will throw the same error as you had in the first constraint we discussed in this post. 

  Best regards,
  Simran

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