This commit is contained in:
UmbertoJr 2019-12-02 08:25:20 +01:00
parent 9024e5d574
commit dd5fd385ab
2 changed files with 58 additions and 3 deletions

View file

@ -20,7 +20,8 @@ class Solver_TSP:
}
available_improvements = {"2-opt": TwoOpt.loop2opt,
"2.5-opt": TwoDotFiveOpt.loop2dot5opt}
"2.5-opt": TwoDotFiveOpt.loop2dot5opt,
"simulated_annealing": Simulated_Annealing.sm}
# ,
# "simulated_annealing": Simulated_Annealing,

View file

@ -1,7 +1,61 @@
import numpy as np
if 'AI' in os.getcwd():
from src.utils import *
else:
from AI2019.src.utils import *
class Simulated_Annealing:
def __call__(self):
pass
@staticmethod
def sa(solution, instance, constant_temperature=0.95, iterations_for_each_temp=100):
# initial setup
temperature = instance.best_sol / np.sqrt(instance.nPoints)
current_sol = solution
current_len = compute_lenght(solution, instance.dist_matrix)
best_sol = solution
best_len = current_len
# main loop
while temperature > 0.001:
for it in range(iterations_for_each_temp):
next_sol, delta_E = Simulated_Annealing.random_sol_from_neig(current_sol, instance)
if delta_E < 0:
current_sol = next_sol
current_len += delta_E
if current_len < best_len:
best_sol = current_sol
else:
r = np.random.uniform(0, 1)
if r < np.exp(- delta_E / temperature):
current_sol = next_sol
current_len += delta_E
temperature *= constant_temperature
return best_sol.tolist()
@staticmethod
def random_sol_from_neig(solution, instance):
i, j = np.random.choice(np.arange(1, len(solution) - 1), 2, replace=False)
i, j = np.sort([i, j])
return Simulated_Annealing.swap2opt(solution, i, j), Simulated_Annealing.gain()
@staticmethod
def swap2opt(tsp_sequence, i, j):
new_tsp_sequence = np.copy(tsp_sequence)
new_tsp_sequence[i:j + 1] = np.flip(tsp_sequence[i:j + 1], axis=0) # flip or swap ?
return new_tsp_sequence
@staticmethod
def gain(i, j, tsp_sequence, matrix_dist):
old_link_len = (matrix_dist[tsp_sequence[i], tsp_sequence[i - 1]] + matrix_dist[
tsp_sequence[j], tsp_sequence[j + 1]])
changed_links_len = (matrix_dist[tsp_sequence[j], tsp_sequence[i - 1]] + matrix_dist[
tsp_sequence[i], tsp_sequence[j + 1]])
return - old_link_len + changed_links_len
class Iterated_Local_Search: