Using gurobi optimize variable

Answered

Ramesh singh

• February 20, 2023 10:52

In the below code, A[i,k] is optimize variable (decision).  This decision variable will change the value of PN.  So i am trying to update the PN for when A[i][k] ==1. For example if M is 5 and P is 15, then it decides the which which k is best A[1][1], A[1][2], A[1][3], A[1][4], A[1][5] such that  A[1][1]+A[1][2]+ A[1][3]+A[1][4]+ A[1][5]=1

i am getting the following error (#error line) "TypeError: unsupported operand type(s) for -=: 'NoneType' and 'float' " in the constrs line. Kindly help to figure out mistake. 

A_initial=nmp1.array([0,1,2,3,1,2,3,1,2,3,4,5,3,4,5,3,4]) #1 to 16, index 0 is unused
PN= nmp1.array([[0,0,0,0,0,0,0,0,0],[0,1,2,3,4,5,6,7,8],[0,9,10,11,12,13,14,15,16]]) # PN[1], PN[2], PN[0] unused
CR=[0,1,1,1,2,2]

bw=nmp.uniform(1,1000,size=(16,5)) # matrix bw[1][1], bw[1][2]....bw[1][5], bw[2][1],....

for i in range(1,16):
    for j in range(1,6):
        A[i][j].Start=0
for i in range(1,16):
    A[i][A_initial[i]]=1
 

 for i in range(1,16):
    m.addConstr(t[i]==(t1[i]+ sum(bw[i,k]*A[i,k] for k in range(1,M+1))),"t") #optimize
   

for j in range(1,R+1):
    for i in range(1,P+1):
        PN[j,i]=0 
for i in range(1,P+1):
    for k in range(1,M+1):
        m.addConstr((A[i,k]==1) >> (PN[CR[k],i]==1)) #error line

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• Python

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• 

  Marika Karbstein

  Gurobi Staff

  • February 21, 2023 10:34

  Your example is not reproducible. But I think the issue is that you need to define PN as Gurobi variables as well if you want to change the values.

  This is not possible:

  A= m.addVar(vtype='B')
  B= 3
  m.addConstr((A==1) >> (B==2))

  and will produce the error

   TypeError: unsupported operand type(s) for -=: 'NoneType' and 'float'

  B needs to be defined as a variable as well

  A= m.addVar(vtype='B')
  B= m.addVar(vtype='I')
  m.addConstr((A==1) >> (B==2))

  0

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