key Error in objective function

Answered

Ashrafur Rahman

November 07, 2021 06:17

• 
• 

I am trying to formulate an objective function but getting a key error. I have tried to unpack the tuple but it's giving me a syntax error. Could anyone help me figure this out?

The issue is with  variable u[o,d,a]. 

o and d are lists with single elements, but a is a list with tuples. I am getting the following key error: 

KeyError: (14, 4, (1, 2))

I guess I need to have (14,4,1,2) but because A is a list of tuple, I am getting the above key error. I tried to unpack the tuple using quicksum((c[a]*u[o,d,*a]), but it is showing syntax error. Any help would be really appreciated.

# Variables: 
y=mdl.addVars(D,vtype=GRB.BINARY,name="y")
x=mdl.addVars(O,D,vtype=GRB.INTEGER,name='x')
w=mdl.addVars(O,vtype=GRB.INTEGER,name="w")
z=mdl.addVars(A,vtype=GRB.BINARY, name="z") 
u=mdl.addVars(O,D,A,vtype=GRB.BINARY, name="u")
v=mdl.addVars(O,D,A,vtype=GRB.INTEGER, name="v")

#objective
obj=quicksum(f[d]*y[d] for d in D)+ quicksum( g[a]*z[a] for a in A) + quicksum((c[a]*u[o,d,a]) for a in A for o in O for d in D )+quicksum(alpha*w[o] for o in O)

0

• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  June 23, 2025 02:45 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

  November 08, 2021 15:21

  Could you also post the definition of \(\texttt{O,D,}\) and \(\texttt{A}\) to make the example reproducible?

  Did you try accessing the values of \(\texttt{u}\) via

  u[o,d,a[0],a[1]]

  Best regards,
  Jaromił

  0

Post is closed for comments.