Include range of costs instead of a single value into the objective function

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Ansari Aadil Shahzad

2022年11月23日 05:50

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Hi,

I am doing an hourly optimization using gurobipy for multiple variables. The sample code I am using is as follows:

Parameters:

AA = ['a', 'b']

price_a = 1

price_b = 2

price_AA = dict(zip(AA,[price_a, price_b]))

min_lim_AA = dict(zip(AA, [0, 0]))

max_lim_AA = dict(zip(AA, [np.inf, np.inf]))

Optimization equation:

prob = grb.Model("Optimization")
prob.modelSense = grb.GRB.MINIMIZE

AAcap  = prob.addVars(AA, obj = 0.0, lb=min_lim_AA , ub=max_lim_AA ,
                        vtype = grb.GRB.CONTINUOUS, name = 'AA Capacity) 

AAout  = prob.addVars(AA, time_index, obj = 0.0, lb=min_lim_AA , ub=max_lim_AA ,

               vtype = grb.GRB.CONTINUOUS, name = 'AA Output)    

for c, t in itertools.product(A, time_index):
    AAout[c,t].obj = price_AA[c]

prob.update()

 

Instead of one value for price_a and price_b, I want to use different values for different hours in the time_index. When I do that (by inputting the values in a CSV format and linking it to the code with csv_reader)  and modify the objective constraint as shown below:

AAout  = prob.addVars(AA, time_index, obj = 0.0, lb=min_lim_AA , ub=max_lim_AA ,

               vtype = grb.GRB.CONTINUOUS, name = 'AA Output)    

for c, t in itertools.product(A, time_index):
    AAout[c,t].obj = price_AA[c][t]

the error that I get is :

AttributeError: Attribute 'obj' takes double value

How can I solve this issue?

 

関連

• Error
• Python

0

• 

  Jaromił Najman

  • Gurobi Staff

  2022年11月23日 11:43

  Hi Ansari,

  It looks like your \(\texttt{price_AA[c][t]}\) values are not doubles. You could try printing them to see what they actually are

  for c, t in itertools.product(A, time_index):
      print(price_AA[c][t])
      AAout[c,t].obj = price_AA[c][t]

  Best regards, 
  Jaromił

  0

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