How to Code a parameter in Gurobi/python interface
Answered
I have a model with some parameters, variables, and constraints. I have a problem mainly in coding the f parameter that required in a specific set of constraints. Indeed, this shown in the image below constraint # 6 causing me the big problem in the whole code.
I tried to code the constraints but failed to code the f parameter, any idea or guide? thank you in advance......
```
n = 5
R = [i for i in range(1,n+1)]
Cr = {1: C[0:3], 2 : C[3:6],3: C[6:9], 4: C[9:12], 5:C[12:15] }
N = list(range(0,27))
# variables related to constraints # 6
for r in R:
yr = m.addVars(N,N, vtype=GRB.BINARY)
for r in R:
z = m.addVars(Cr[r],Cr[r],vtype=GRB.BINARY)
m.update()
# Constraint #6
for r in R:
m.addConstrs(((quicksum(yr[i,j] for j in N if j !=i) + quicksum(z [i,j] for j in Cr[r] if j !=i)- quicksum(yr[j,i] for j in N if j !=i)- quicksum(z [j,i] for j in Cr[r]if j !=i ) == f[i]) for i in Cr[r] ),'6')
```
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Gurobi Staff
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I have not looked at the last line in detail, however note the following:
- The first for loop does not use the variable r, therefore it just creates the same 2D-array of variables over and over again.
- You do not need to call m.update() at each step of the second for loop (in fact, you don't need to call it at all)
- The last line needs to be indented, otherwise it is not valid Python syntax.
- In your minimum working example, you do not describe C nor f, so it is not possible to make sure that the implementation of eq. (6) is correct.
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