Help: GurobiError: Unrecognized argument to getAttr
Answeredimport gurobipy as gp
from gurobipy import GRB
import math
numiter = 10
lambdak = 0
alphak = 1.0
zstar = 0
betak = 2
zstarvals = []
lambdavals = []
zlkprev= math.inf
rediter = 1
m = gp.Model('LagrangianRelaxation')
X1 = m.addVar(vtype=GRB.INTEGER, name='X1')
X2 = m.addVar(vtype=GRB.INTEGER, name='X2')
X3 = m.addVar(vtype=GRB.INTEGER, name='X3')
X4 = m.addVar(vtype=GRB.INTEGER, name='X4')
m.addConstr(X1 + X2 <= 1 , "Constraint1")
m.addConstr(X3 + X4 <= 1 , "Constraint2")
LR = (8*lambdak - 16)*X1 + (2*lambdak - 10)*X2 + lambdak*X3 + (4*lambdak - 4)*X4
m.setObjective(LR , GRB.MAXIMIZE)
for i in range (0,numiter):
print(str(i) + "started")
m.optimize()
if m.status == GRB.OPTIMAL:
X1out = m.getAttr('x', X1)
X2out = m.getAttr('x', X2)
X3out = m.getAttr('x', X3)
X4out = m.getAttr('x', X4)
Hello,
I'm new to optimization/Gurobi and trying to learn. The code block above errors at the getAttr lines with the following message:
GurobiError: Unrecognized argument to getAttr
What is the issue here? I have used the same format in another optimization problem and that works just fine. Can someone help please?
Thanks in advance!
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Hi Abhishek,
The Model.getAttr function expects a list or dictionary of gurobipy modelling objects as its second object, you cannot pass a single variable object. The following will return a list of the solution values for X1 -> X4, in order:
m.getAttr('X', [X1, X2, X3, X4])Alternatively, you can access the solution values one by one using the 'X' attribute of the variables themselves:
X1out = X1.X
X2out = X2.X
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Thank you Simon!
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