7 from xlrd
import open_workbook
18 a(i) capacity of plant i in cases
19 b(j) demand at market j in cases
20 d(i,j) distance in thousands of miles
21 Scalar f freight in dollars per case per thousand miles /90/;
23 $if not set gdxincname $abort 'no include file name for data file provided'
28 Parameter c(i,j) transport cost in thousands of dollars per case ;
30 c(i,j) = f * d(i,j) / 1000 ;
33 x(i,j) shipment quantities in cases
34 z total transportation costs in thousands of dollars ;
39 cost define objective function
40 supply(i) observe supply limit at plant i
41 demand(j) satisfy demand at market j ;
43 cost .. z =e= sum((i,j), c(i,j)*x(i,j)) ;
45 supply(i) .. sum(j, x(i,j)) =l= a(i) ;
47 demand(j) .. sum(i, x(i,j)) =g= b(j) ;
49 Model transport /all/ ;
51 Solve transport using lp minimizing z ;
53 Display x.l, x.m ; '''
56 if __name__ ==
"__main__":
57 wb = open_workbook(
"..\\Data\\transport.xlsx")
59 capacity = wb.sheet_by_name(
"capacity")
60 demand = wb.sheet_by_name(
"demand")
61 distance = wb.sheet_by_name(
"distance")
64 assert (distance.ncols-1 == demand.ncols)
and (distance.nrows-1 == capacity.ncols), \
65 "Size of the spreadsheets doesn't match"
68 ws = GamsWorkspace(system_directory = sys.argv[1])
72 db = ws.add_database()
73 i = db.add_set(
"i", 1,
"Plants")
74 j = db.add_set(
"j", 1,
"Markets")
75 capacity_param = db.add_parameter_dc(
"a", [i],
"Capacity")
76 demand_param = db.add_parameter_dc(
"b", [j],
"Demand")
77 distance_param = db.add_parameter_dc(
"d", [i,j],
"Distance")
79 for cx
in range(capacity.ncols):
80 i.add_record(str(capacity.cell_value(0, cx)))
81 capacity_param.add_record(str(capacity.cell_value(0, cx))).value = capacity.cell_value(1, cx)
83 for cx
in range(demand.ncols):
84 j.add_record(str(demand.cell_value(0, cx)))
85 demand_param.add_record(str(demand.cell_value(0, cx))).value = demand.cell_value(1, cx)
87 for cx
in range(1, distance.ncols):
88 for rx
in range(1, distance.nrows):
89 keys = ( str(distance.cell_value(rx, 0)), str(distance.cell_value(0, cx)) )
90 distance_param.add_record(keys).value = distance.cell_value(rx, cx)
94 opt = ws.add_options()
95 opt.defines[
"gdxincname"] = db.name
96 opt.all_model_types =
"xpress"
97 t10.run(opt, databases=db)
98 for rec
in t10.out_db[
"x"]:
99 print(
"x(" + rec.key(0) +
"," + rec.key(1) +
"): level=" + str(rec.level) +
" marginal=" + str(rec.marginal))