Getting TypeError: zip argument #1 must support iteration

[nooshin valibeig]

Hi Everyone 

I have modeled an optimization problem in Gurobi-Python, for one of my constraints I have got the below error. How can resolve this error?

CONSTRAINT:

for p in person:

        m.addConstr(quicksum((regAssign[time[t],p]  + irregAssign[time[t],p]) for t in range(startTime[p]-1,startTime[p] + lengthOfTime[p] + 1)) <= lengthOfTime[p] + 1, 'not more than LOT+1 %s' % p)

ERROR:

Traceback (most recent call last):

  File "<string>", line 254, in run_nodebug

  File "C:\Working Project1\SimulatedDataForModel.py", line 102, in <module>

    ConnectingTwoFiles.solve(time, person, startTime, lengthOfTime, regular , irregular )

  File "C:\Working Project1\ConnectingTwoFiles.py", line 50, in solve

    m.addConstr(quicksum((regAssign[time[t],p]  + irregAssign[time[t],p]) for t in range(startTime[p]-1,startTime[p] + lengthOfTime[p] + 1)) <= lengthOfTime[p] + 1, 'not more than LOT+1 %s' % p)

  File "var.pxi", line 253, in gurobipy.Var.__radd__ (../../src/python/gurobipy.c:9499)

  File "exprutil.pxi", line 15, in gurobipy.__exprsum (../../src/python/gurobipy.c:27792)

  File "linexpr.pxi", line 37, in gurobipy.LinExpr.__init__ (../../src/python/gurobipy.c:16485)

TypeError: zip argument #1 must support iteration

Thanks,

Nooshin

[Jakob Sch.]

Hi Nooshin,

My first guess would be that you do not use quicksum() correctly. It should be called with a list of terms. Try

for p in person:

        m.addConstr(quicksum([regAssign[time[t],p]  + irregAssign[time[t],p] for t in range(startTime[p]-1,startTime[p] + lengthOfTime[p] + 1)]) <= lengthOfTime[p] + 1, 'not more than LOT+1 %s' % p)

Best regards,
Jakob