I want to solve some linear programming with gurobipy but there is error on and on. I'm pretty new to Python so it might be obvious but I can't seem to find my error. Here is my code ``` import gurobipy as gp from gurobipy import GRB
# In[4]:
import numpy as np
import pandas as pd
time_shifts = list(range(1,11))
num_turbine=list(range(1,10))
I = ['t1','t2']
NP=['t1']
NC = ['t2']
Wmax = 7
Qmax = 3
Vmax = 4
PPi = {'t1':80}
Ut = 10
Cteam = 1200000
TR = 3
HDT = [439517,530261,490784,530325,629710,556702,562887,493247,449940,479517]
DT = [element * 24 * 7 for element in HDT]
EH = {1:HDT[0], 2:HDT[1], 3:HDT[2], 4:HDT[3], 5:HDT[4], 6:HDT[5], 7:HDT[6], 8:HDT[7],
9:HDT[8], 10:HDT[9]}
ED = {1:DT[0], 2:DT[1], 3:DT[2], 4:DT[3], 5:DT[4], 6:DT[5], 7:DT[6], 8:DT[7],
9:DT[8], 10:DT[9]}
Ni = {'t1': 5,'t2': 18}
At = {1:6,2:5,3:5,4:2,5:3,6:7,7:4,8:6,9:6,10:7}
Wt= {1:4,2:4,3:4,4:4,5:4,6:4,7:4,8:4,9:4,10:4}
Cvt = {}
for i in range(1,11):
Cvt[i] = At[i]*300*1000*TR
Git = {('t2',1):7,('t2',2):7,('t2',3):7,('t2',4):7,('t2',5):8,('t2',6):8,('t2',7):8,
('t2',8):9,('t2',9):8,('t2',10):7}
SGit = {('t2',1):7,('t2',2):14,('t2',3):21,('t2',4):28,('t2',5):36,('t2',6):44,('t2',7):52,
('t2',8):61,('t2',9):69,('t2',10):76}
m = gp.Model('Offshore')#Xit
xitb = m.addVars(NP, time_shifts,num_turbine,lb=0, name = "preventive",vtype=GRB.BINARY)
#Yitb
yitb = m.addVars(NC, time_shifts,num_turbine,lb=0, name = "corrective",vtype=GRB.BINARY)
#Wit
witb = m.addVars(NC, time_shifts,num_turbine,lb=0, name = "requiring",vtype=GRB.BINARY)
#Zt
zt = m.addVars(time_shifts,lb=0,ub = Qmax, name = "vessel",vtype=GRB.INTEGER)
#ut
ut = m.addVars(time_shifts,lb=0,ub = Ut, name = "team",vtype=GRB.INTEGER)
m.addConstrs(gp.quicksum(witb[i,t,b])<=SGit[i,t] for i in NC for t in time_shifts for b in num_turbine)
m.addConstrs(gp.quicksum(xitb[i,t,b]**Ni[i])+gp.quicksum(yitb[j,t,b]**Ni[j])<=Wt[t]*ut[t]*Wmax for i in NP for t in time_shifts for b in num_turbine for j in NC)
m.addConstrs((gp.quicksum(xitb[i,t,b]**Ni[i] for i in NC for t in time_shifts for b in num_turbine)+gp.quicksum(yitb[j,t,b]**Ni[j])+ut[t]*Wt[t]*TR)<=ut[t]*40 for t in time_shifts for j in NC for b in num_turbine)
time_shift2 = list(range(2,53))
m.addConstrs(gp.quicksum(witb[j,t,b])==gp.quicksum(witb[j,t-1,b] for j in NC for t in time_shift2 for b in num_turbine )-gp.quicksum(yitb[j,t,b] )+Git[j,t] for j in NC for t in time_shift2 for b in num_turbine )
m.addConstrs( Git[i,1] - yitb[i,1]==witb[i,1] for i in NC )
m.addConstrs(Git[i,1]-gp.quicksum(yitb[i,1,b])==gp.quicksum(witb[i,1,b]) for b in num_turbine)
m.addConstrs(gp.quicksum(yitb[j,t,b] for j in NC for t in time_shift2 for b in num_turbine)<=gp.quicksum(witb[j,t,b])+Git[j,t] for j in NC for t in time_shift2 for b in num_turbine )
m.addConstrs(gp.quicksum(xitb[i,t,b])==PPi[i] for i in NP for t in time_shifts for b in num_turbine)
m.addConstr(gp.quicksum(xitb[i,t,b] for i in NP for b in num_turbine for t in list(range(10,41))) >= 100*(2/3) )
m.addConstrs((ut[t]/Vmax) <= zt[t] for t in time_shifts)
obj = gp.quicksum(Cvt[t]*zt[t] + Cteam*ut[t] +
EH[t]*Ni[P]*xitb[P,t,b] + ED[t]*witb[C,t,b] for P in NP for C in NC for t in time_shifts for b in num_turbine )
m.setObjective(obj, GRB.MINIMIZE)
m.optimize()
for v in m.getVars():
print('%s %g' % (v.varName, v.x))
```
The part that not working is:
```
m.addConstrs(gp.quicksum(witb[i,t,b])<=SGit[i,t] for i in NC for t in time_shifts for b in num_turbine)
```
First constraint is wrong. I think there are fundamentally fault. However I don's know where is. Additionally about in first constraint i want to express like this w(t2,1,1)+w(t2,1,2).....w(t2,1,9)<=SGit(t2,1), w(t2,2,1)+w(t2,2,2).....w(t2,2,9)<=SGit(t2,2),... w(t2,10,1)+w(t2,10,1)....w(t2,10,10)<=SGit(t2,10)
The quicksum method expects a generator expression or a list, not a single variable. Similarly, addConstrs also expects a generator expression. Hence, your first constraints should be written like this (note the extra bracket)
from gurobipy import quicksum as qsum
# ... rest of your code ...
m.addConstrs((qsum(withb[i,t,b] for b in num_turbine) <= SGit[i,t]) for i in NC for t in time_shifts)
IMHO, writing your constraints with loops and the addConstr method instead is less error-prone and makes reading your code easier:
from gurobipy import quicksum as qsum
for i in NC:
for t in time_shifts:
m.addConstr(qsum(withb[i,t,b] for b in num_turbine) <= SGit[i,t])