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January 25, 2019 06:51
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pure fixed charge transportation problem
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from pulp import * | |
def solve(): | |
left = list(range(10)) | |
right = list(range(10)) | |
route = [(i, j) for i in left for j in right] | |
supply = [8, 6, 7, 10, 11, 13, 6, 13, 14, 12] | |
demand = [11, 11, 10, 7, 10, 11, 13, 9, 9, 9] | |
assert(sum(supply) == sum(demand)) | |
# 枝(i, j)を使う定数コストはすべて1 | |
costs = [[1] * len(right) for _ in range(len(left))] | |
costs = makeDict([left, right], costs, 0) | |
M = [[0] * len(right) for i in range(len(left))] | |
for i in left: | |
for j in right: | |
M[i][j] = min(supply[i], demand[j]) | |
M = makeDict([left, right], M, 0) | |
x = LpVariable.dicts(name="flow", indexs=route, lowBound=0, cat=LpInteger) # 枝(i,j)に流れる量 | |
y = LpVariable.dicts(name="use", indexs=route, cat=LpBinary) # 枝(i,j)を使うかどうか | |
prob = LpProblem("PC-FCTP", LpMinimize) | |
prob += lpSum([costs[r[0]][r[1]] * y[r] for r in route]) | |
for i in left: | |
prob += lpSum([x[(i, j)] for j in right]) == supply[i] | |
for j in right: | |
prob += lpSum([x[(i, j)] for i in left]) == demand[j] | |
for r in route: | |
prob += x[r] <= M[r[0]][r[1]] * y[r] | |
prob.solve(PULP_CBC_CMD()) | |
print("Status:{0}".format(LpStatus[prob.status])) | |
print("Total Cost:{0}".format(value(prob.objective))) | |
print("Assignment:") | |
for r in route: | |
if y[r].value() == 1: | |
print("Left:{0} -> Right:{1}({2})".format(r[0], r[1], x[r].value())) | |
def main(): | |
import time | |
start = time.time() | |
solve() | |
print("{0}sec".format(int(time.time() - start))) | |
if __name__ == '__main__': | |
main() |
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