def test_2opt_one_crossed(self):
route = [0, 1, 6, 2, 7, 0]
initial_f = objf(route, self.D)
sol, delta_f = do_2opt_move(route, self.D, LSOPT.BEST_ACCEPT)
do_2opt_f = objf(sol, self.D)
self.assertEqual(
sol, [0, 1, 2, 6, 7, 0],
"chose invalid move, initial %f, optimized %f" %
(initial_f, do_2opt_f))
self.assertEqual(
initial_f + delta_f, do_2opt_f,
"The delta based and recalculated objective functions differ")
def inspect_heuristic(routes, D, C, d, L):
improvement_found = False
for rd in routes:
if rd.is_empty():
continue
delta = 0.0
while delta is not None:
new_route, delta = do_2opt_move(rd.route, D, FAS)
if delta is not None:
rd.route = new_route
rd.cost += delta
improvement_found = True
return improvement_found
def test_2opt_two_crossed(self):
route = [0, 1, 6, 3, 4, 5, 2, 7, 0]
required_moves = 2
for i in range(required_moves):
#print "op %d:"%i+1
#print "initial f =",f(route,self.D)
opt_route, opt_f = do_2opt_move(route, self.D, LSOPT.BEST_ACCEPT)
#print "2-opt'd f =",f(opt_route,self.D)
if opt_route is None:
return route
else:
route = opt_route
self.assertEqual(i + 1, required_moves)
self.assertEqual(opt_route, [0, 1, 2, 3, 4, 5, 6, 7, 0])
def solve_tsp_ropt(D,
selected_idxs,
do_shuffle=False,
do2opt=True,
do3opt=True):
# r-Opt (r \in {2,3} )
endp = selected_idxs[0]
if do_shuffle:
shuffled_idxs = list(selected_idxs[1:])
shuffle(shuffled_idxs)
new_route = [endp] + shuffled_idxs + [endp]
elif selected_idxs[-1] != endp:
new_route = selected_idxs + [endp]
else:
new_route = selected_idxs
new_route_cost = objf(new_route, D)
# make first 2-optimal
if do2opt:
improved = True
while improved:
improved = False
improved_route, delta = do_2opt_move(new_route, D, 1)
if improved_route is not None:
new_route = improved_route
new_route_cost += delta
improved = True
# then 3-optimal (do not waste time on "easy" 2-opt
# operations if the route has already been made 2-optimal
if do3opt:
improved = True
while improved:
improved = False
improved_route, delta = do_3opt_move(new_route, D, 1)
if improved_route is not None:
new_route = improved_route
new_route_cost += delta
improved = True
return new_route, new_route_cost
def test_2opt_none_crossed(self):
route = [0, 1, 2, 3, 0]
sol, delta_f = do_2opt_move(route, self.D)
self.assertEqual(
sol, None,
"Route was already 2-optimal, improvements are not possible")
def test_empty_route(self):
self.assertEqual(do_2opt_move([], self.D), (None, None))
self.assertEqual(do_2opt_move([0, 0], self.D), (None, None))
def _try_insert_2opt_and_update(insertion, rd, D, L, minimize_K):
inserted = rd.route.insert(insertion.customer, insertion.before_node)
#print("inserting", insertion, "resulting to", list(rd.route))
## keep the route 2-optimal
# unfortunately we cannot do local_search.py do_2opt_move on the reoute,
# because it is an dllist. However, as the route is kept 2-optimal, it
# is probable that not all search attempts lead to updating the route,
# so convert and udpate only as needed.
route_2opt_improved = list(rd.route)
total_delta = insertion.cost_delta
applied_2opt_moves = False
while True:
updated_route, delta = do_2opt_move(route_2opt_improved,
D,
strategy=LSOPT.BEST_ACCEPT)
if delta is not None:
applied_2opt_moves = True
total_delta += delta
route_2opt_improved = updated_route
else:
break
# do not accept insertions/moves that make the solution worse!
if not minimize_K:
# Compared to a solution where the customer is served individually
insertion_cost = total_delta - D[0, insertion.customer] - D[
insertion.customer, 0]
if insertion_cost > 0:
if __debug__:
log(DEBUG - 2,
("Rejecting insertion of n%d " % insertion.customer) +
("as it is expected make solution worse."))
rd.route.remove(inserted) # reverse the change
return False, None
if L and rd.cost + total_delta - S_EPS > L:
# The L constraint cannot be satisfied, even with 2-opt
rd.route.remove(inserted) # reverse the change
return False, None
rd.cost += total_delta
rd.used_capacity += insertion.demand_delta
if applied_2opt_moves:
# this is very ineffective, but as the dllist nodes and next/prev
# are read only, and the llist module does not offer a sequence
# reversing functionality (!) we have no choice but scrap the entire
# insertion queue and calculate the insertions all over for the
# updated route. :(
#
#TODO: an improvement would be to use an another doubly-linked-list
# implementaiton that allows manipulation of the nodes / list
del rd.potential_insertions[:]
updated_dllist = dllist(route_2opt_improved)
new_edges = []
prev_node = updated_dllist.first
current_node = prev_node.next
while prev_node != updated_dllist.last:
new_edges.append((prev_node, current_node))
prev_node = current_node
current_node = prev_node.next
if __debug__:
log(
DEBUG, "Applying a 2-opt moves, which transforms " +
" %s to %s with an %.2f improvement" %
(str(list(rd.route)), str(route_2opt_improved),
total_delta - insertion.cost_delta))
rd.route = updated_dllist
return True, new_edges
else:
new_edges = [(insertion.after_node, inserted),
(inserted, insertion.before_node)]
return True, new_edges