Python纸浆约束

Question

I am trying to add a constraint to linear programming problem in python using pulp library. I tried code below.

for week in range(14,52), i in I.index:
    k = week
    model += sum(x[(i, j, week, B)] for week in range(k, k+13), 
                                        j in J.index) <= 1

where I and J have following indexes

I.index = ['A','B','C']
J.index = [1,2,3]

The error I get is SyntaxError: Generator expression must be parenthesized if not sole argument . I have researched this link Generator expression must be parenthesized if not sole argument however it didn't seem to resolve my issue. Any help is appreciated.

Answer 1

Or Duan's comment looks correct the syntax used should be

for week in range(14,52), i in I.index:
    k = week
    model += sum(x[(i, j, week, B)] for week in range(k, k+13)
                                    for j in J.index) <= 1

but in this case it will be much faster if you use the lpSum() function

for week in range(14,52), i in I.index:
    k = week
    model += lpSum(x[(i, j, week, B)] for week in range(k, k+13)
                                    for j in J.index) <= 1