def two_opt(cost, tour, iterations):
opt_tour = tour.copy()
for _ in range(iterations):
for i in range(len(opt_tour)):
for j in range(i + 2, len(opt_tour) - 1):
if cost[opt_tour[i], opt_tour[i + 1]] + cost[
opt_tour[j], opt_tour[j + 1]] > cost[
opt_tour[i], opt_tour[j]] + cost[opt_tour[i + 1],
opt_tour[j + 1]]:
opt_tour[i + 1:j + 1] = reversed(opt_tour[i + 1:j + 1])
if tour_cost(cost, opt_tour) < tour_cost(cost, tour):
tour = opt_tour
return tour
[32, 0, 21, 29, 76, 40, 43, 41, 36, 37],
[53, 21, 0, 23, 72, 19, 23, 52, 46, 22],
[51, 29, 23, 0, 50, 35, 39, 36, 30, 14],
[84, 76, 72, 50, 0, 79, 83, 51, 51, 53],
[72, 40, 19, 35, 79, 0, 4, 69, 63, 26],
[76, 43, 23, 39, 83, 4, 0, 74, 67, 30],
[33, 41, 52, 36, 51, 69, 74, 0, 6, 50],
[33, 36, 46, 30, 51, 63, 67, 6, 0, 44],
[64, 37, 22, 14, 53, 26, 30, 50, 44, 0]])
cost = np.array([[ 0, 32, 53, 51, 84, 72, 76, 33, 33, 64],
[32, 0, 21, 29, 76, 40, 43, 41, 36, 37],
[53, 21, 0, 23, 72, 19, 23, 52, 46, 22],
[51, 29, 23, 0, 50, 35, 39, 36, 30, 14],
[84, 76, 72, 50, 0, 79, 83, 51, 51, 53],
[72, 40, 19, 35, 79, 0, 4, 69, 63, 26],
[76, 43, 23, 39, 83, 4, 0, 74, 67, 30],
[33, 41, 52, 36, 51, 69, 74, 0, 6, 50],
[33, 36, 46, 30, 51, 63, 67, 6, 0, 44],
[64, 37, 22, 14, 53, 26, 30, 50, 44, 0]])
tour = [i for i in range(len(cost_matrix))]
tour.extend([tour[0]])
depot = 9
print('Original Tour:', tour)
print('Original Tour Cost:', tour_cost(cost_matrix, tour))
insertion_tour = cheapest_insertion(cost_matrix, depot)
insertion_cost = tour_cost(cost, insertion_tour)
print('Nearest Neighbour Tour:', insertion_tour)
print('Nearest Neighbour Tour Cost:', insertion_cost)
print('Computation Time:',(time.clock() - start_time))
[32, 0, 21, 29, 76, 40, 43, 41, 36, 37],
[53, 21, 0, 23, 72, 19, 23, 52, 46, 22],
[51, 29, 23, 0, 50, 35, 39, 36, 30, 14],
[84, 76, 72, 50, 0, 79, 83, 51, 51, 53],
[72, 40, 19, 35, 79, 0, 4, 69, 63, 26],
[76, 43, 23, 39, 83, 4, 0, 74, 67, 30],
[33, 41, 52, 36, 51, 69, 74, 0, 6, 50],
[33, 36, 46, 30, 51, 63, 67, 6, 0, 44],
[64, 37, 22, 14, 53, 26, 30, 50, 44, 0]])
cost = np.array([[0, 32, 53, 51, 84, 72, 76, 33, 33, 64],
[32, 0, 21, 29, 76, 40, 43, 41, 36, 37],
[53, 21, 0, 23, 72, 19, 23, 52, 46, 22],
[51, 29, 23, 0, 50, 35, 39, 36, 30, 14],
[84, 76, 72, 50, 0, 79, 83, 51, 51, 53],
[72, 40, 19, 35, 79, 0, 4, 69, 63, 26],
[76, 43, 23, 39, 83, 4, 0, 74, 67, 30],
[33, 41, 52, 36, 51, 69, 74, 0, 6, 50],
[33, 36, 46, 30, 51, 63, 67, 6, 0, 44],
[64, 37, 22, 14, 53, 26, 30, 50, 44, 0]])
tour = [i for i in range(len(cost_matrix))]
tour.extend([tour[0]])
depot = 0
print('Original Tour:', tour)
print('Original Tour Cost:', tour_cost(cost_matrix, tour))
nn_tour = nn(cost_matrix, depot)
nn_cost = tour_cost(cost, nn_tour)
print('Nearest Neighbour Tour:', nn_tour)
print('Nearest Neighbour Tour Cost:', nn_cost)
print('Computation Time:', (time.clock() - start_time))
if __name__ == "__main__":
# node_array = np.random.random_integers(0,high=10,size=(10,2))
start_time = time.clock()
# adj_matrix = distance_matrix(node_array, node_array, p=2)
# cost = np.random.random_integers(0,high=100,size=(100,100))
cost = np.array([[0, 32, 53, 51, 84, 72, 76, 33, 33, 64],
[32, 0, 21, 29, 76, 40, 43, 41, 36, 37],
[53, 21, 0, 23, 72, 19, 23, 52, 46, 22],
[51, 29, 23, 0, 50, 35, 39, 36, 30, 14],
[84, 76, 72, 50, 0, 79, 83, 51, 51, 53],
[72, 40, 19, 35, 79, 0, 4, 69, 63, 26],
[76, 43, 23, 39, 83, 4, 0, 74, 67, 30],
[33, 41, 52, 36, 51, 69, 74, 0, 6, 50],
[33, 36, 46, 30, 51, 63, 67, 6, 0, 44],
[64, 37, 22, 14, 53, 26, 30, 50, 44, 0]])
tour = [i for i in range(len(cost))]
tour.extend([tour[0]])
print('Original Tour:', tour)
print('Original Tour Cost:', tour_cost(cost, tour))
iterations = 1
opt2_tour = two_opt(cost, tour, iterations)
print('2-opt Tour:', opt2_tour)
print('2-opt Tour Cost:', tour_cost(cost, opt2_tour))
print('Computation Time:', (time.clock() - start_time))
def opt_3(cost, tour, iterations):
opt_tour = tour.copy()
for _ in range(iterations):
for i in range(len(opt_tour) - 1):
for j in range(i + 2, len(opt_tour) - 1):
for k in range(j + 2, len(opt_tour) - 1):
way = 0
current = cost[opt_tour[i], opt_tour[i + 1]] + cost[
opt_tour[j], opt_tour[j + 1]] + cost[opt_tour[k],
opt_tour[k + 1]]
if current > cost[opt_tour[i], opt_tour[i + 1]] + cost[
opt_tour[j], opt_tour[k]] + cost[opt_tour[j + 1],
opt_tour[k + 1]]:
current = cost[opt_tour[i], opt_tour[i + 1]] + cost[
opt_tour[j], opt_tour[k]] + cost[opt_tour[j + 1],
opt_tour[k + 1]]
way = 1
if current > cost[opt_tour[i], opt_tour[j]] + cost[
opt_tour[i + 1], opt_tour[j + 1]] + cost[
opt_tour[k], opt_tour[k + 1]]:
current = cost[opt_tour[i], opt_tour[j]] + cost[
opt_tour[i + 1],
opt_tour[j + 1]] + cost[opt_tour[k],
opt_tour[k + 1]]
way = 2
if current > cost[opt_tour[i], opt_tour[j]] + cost[
opt_tour[i + 1], opt_tour[k]] + cost[
opt_tour[j + 1], opt_tour[k + 1]]:
current = cost[opt_tour[i], opt_tour[j]] + cost[
opt_tour[i + 1],
opt_tour[k]] + cost[opt_tour[j + 1],
opt_tour[k + 1]]
way = 3
if current > cost[opt_tour[i], opt_tour[j + 1]] + cost[
opt_tour[k], opt_tour[i + 1]] + cost[
opt_tour[j], opt_tour[k + 1]]:
current = cost[opt_tour[i], opt_tour[j + 1]] + cost[
opt_tour[k],
opt_tour[i + 1]] + cost[opt_tour[j],
opt_tour[k + 1]]
way = 4
if current > cost[opt_tour[i], opt_tour[j + 1]] + cost[
opt_tour[k], opt_tour[j]] + cost[opt_tour[i + 1],
opt_tour[k + 1]]:
current = cost[opt_tour[i], opt_tour[j + 1]] + cost[
opt_tour[k], opt_tour[j]] + cost[opt_tour[i + 1],
opt_tour[k + 1]]
way = 5
if current > cost[opt_tour[i], opt_tour[k]] + cost[
opt_tour[j + 1], opt_tour[i + 1]] + cost[
opt_tour[j], opt_tour[k + 1]]:
current = cost[opt_tour[i], opt_tour[k]] + cost[
opt_tour[j + 1],
opt_tour[i + 1]] + cost[opt_tour[j],
opt_tour[k + 1]]
way = 6
if current > cost[opt_tour[i], opt_tour[k]] + cost[
opt_tour[j + 1], opt_tour[j]] + cost[
opt_tour[i + 1], opt_tour[k + 1]]:
current = cost[opt_tour[i], opt_tour[k]] + cost[
opt_tour[j + 1],
opt_tour[j]] + cost[opt_tour[i + 1],
opt_tour[k + 1]]
way = 7
if way == 1:
opt_tour[j + 1:k + 1] = reversed(opt_tour[j + 1:k + 1])
elif way == 2:
opt_tour[i + 1:j + 1] = reversed(opt_tour[i + 1:j + 1])
elif way == 3:
opt_tour[i + 1:j +
1], opt_tour[j + 1:k + 1] = reversed(
opt_tour[i + 1:j + 1]), reversed(
opt_tour[j + 1:k + 1])
elif way == 4:
opt_tour = opt_tour[:i + 1] + opt_tour[
j + 1:k + 1] + opt_tour[i + 1:j + 1] + opt_tour[k +
1:]
elif way == 5:
temp = opt_tour[:i + 1] + opt_tour[j + 1:k + 1]
temp += reversed(opt_tour[i + 1:j + 1])
temp += opt_tour[k + 1:]
opt_tour = temp
elif way == 6:
temp = opt_tour[:i + 1]
temp += reversed(opt_tour[j + 1:k + 1])
temp += opt_tour[i + 1:j + 1]
temp += opt_tour[k + 1:]
opt_tour = temp
elif way == 7:
temp = opt_tour[:i + 1]
temp += reversed(opt_tour[j + 1:k + 1])
temp += reversed(opt_tour[i + 1:j + 1])
temp += opt_tour[k + 1:]
opt_tour = temp
if tour_cost(cost, opt_tour) < tour_cost(cost, tour):
tour = opt_tour
return tour
# return path
if __name__ == "__main__":
# node_array = np.random.random_integers(0,high=10,size=(10,2))
start_time = time.clock()
# adj_matrix = distance_matrix(node_array, node_array, p=2)
# cost = np.random.random_integers(0,high=100,size=(100,100))
cost = np.array([[0, 32, 53, 51, 84, 72, 76, 33, 33, 64],
[32, 0, 21, 29, 76, 40, 43, 41, 36, 37],
[53, 21, 0, 23, 72, 19, 23, 52, 46, 22],
[51, 29, 23, 0, 50, 35, 39, 36, 30, 14],
[84, 76, 72, 50, 0, 79, 83, 51, 51, 53],
[72, 40, 19, 35, 79, 0, 4, 69, 63, 26],
[76, 43, 23, 39, 83, 4, 0, 74, 67, 30],
[33, 41, 52, 36, 51, 69, 74, 0, 6, 50],
[33, 36, 46, 30, 51, 63, 67, 6, 0, 44],
[64, 37, 22, 14, 53, 26, 30, 50, 44, 0]])
tour = [i for i in range(len(cost))]
tour.extend([tour[0]])
print('Original Tour:', tour)
print('Original Tour Cost:', tour_cost(cost, tour))
iterations = 1
opt3_tour = opt_3(cost, tour, iterations)
print('3-opt Tour:', opt3_tour)
print('3-opt Tour Cost:', tour_cost(cost, opt3_tour))
print('Computation Time:', (time.clock() - start_time))