def visualize_3opt_move_s1_r2_s3(D, pts, optimum):
""" Test the 2nd 3-opt alternative (actually corresponding a 2-opt
move), where the middle segment (segment2) is reversed."""
# modify the distance matrix to force a recombination move
D = D.copy()
_set_weight(D, 2, 3, 100)
_set_weight(D, 8, 9, 100)
_set_weight(D, 2, 8, 1)
_set_weight(D, 3, 9, 1)
initial_sol = optimum
sol = do_3opt_move(initial_sol, D)
_visualize_result("output/3opt_move2_s1_r2_s3.dot", sol, pts, D)
def visualize_3opt_move_s1_s2_r3(D, pts, optimum):
""" Test the 1st 3-opt alternative (actually corresponding a 2-opt
move), where the last segment (segment3) is reversed."""
# modify the distance matrix to force a recombination move
D = D.copy()
_set_weight(D, 8, 9, 100)
_set_weight(D, 16, 17, 100)
_set_weight(D, 8, 16, 1)
_set_weight(D, 9, 17, 1)
initial_sol = optimum
sol = do_3opt_move(initial_sol, D)
_visualize_result("output/3opt_move1_s1_s2_r3.dot", sol, pts, D)
def visualize_3opt_move_s1_r2_r3(D, pts, optimum):
""" Test the 4th 3-opt alternative, where the middle AND last segments
(segment2 and segment3) are both reversed but their order kept."""
# modify the distance matrix to force a recombination move
D = D.copy()
_set_weight(D, 2, 3, 100)
_set_weight(D, 8, 9, 100)
_set_weight(D, 16, 17, 100)
_set_weight(D, 2, 8, 1)
_set_weight(D, 3, 16, 1)
_set_weight(D, 9, 17, 1)
initial_sol = optimum
sol = do_3opt_move(initial_sol, D)
_visualize_result("output/3opt_move4_s1_r2_r3.dot", sol, pts, D)
def visualize_3opt_move_s1_r3_r2(D, pts, optimum):
""" Test the 3rd 3-opt alternative (actually corresponding a 2-opt
move), where the first segment (segment1) is reversed. However, in
symmetric case this is equal to reversing the order and direction of
the segments 2 and 3 and this is the expected move operation here."""
# modify the distance matrix to force a recombination move
D = D.copy()
_set_weight(D, 2, 3, 100)
_set_weight(D, 16, 17, 100)
_set_weight(D, 2, 16, 1)
_set_weight(D, 3, 17, 1)
initial_sol = optimum
sol = do_3opt_move(initial_sol, D)
_visualize_result("output/3opt_move3_s1_r3_r2.dot", sol, pts, D)
def visualize_3opt_move_s1_r3_s2(D, pts, optimum):
"""Test the 7th and final 3-opt alternative, where the middle AND last segments
(segment2 and segment3) are swapped, and the segment3 is reversed."""
# modify the distance matrix to force a recombination move
D = D.copy()
_set_weight(D, 2, 3, 100)
_set_weight(D, 8, 9, 100)
_set_weight(D, 16, 17, 100)
_set_weight(D, 2, 16, 1)
_set_weight(D, 9, 3, 1)
_set_weight(D, 8, 17, 1)
initial_sol = optimum
sol = do_3opt_move(initial_sol, D)
_visualize_result("output/3opt_move7_s1_r3_s2.dot", sol, pts, D)
def visualize_3opt_move_s1_s3_s2(D, pts, optimum):
""" Test the 5th 3-opt alternative, where the middle AND last segments
(segment2 and segment3) are swapped, but their traverse direction kept."""
# modify the distance matrix to force a recombination move
D = D.copy()
_set_weight(D, 2, 3, 100)
_set_weight(D, 8, 9, 100)
_set_weight(D, 16, 17, 100)
_set_weight(D, 2, 9, 1)
_set_weight(D, 16, 3, 1)
_set_weight(D, 8, 17, 1)
initial_sol = optimum
sol = do_3opt_move(initial_sol, D)
_visualize_result("output/3opt_move5_s1_s3_s2.dot", sol, pts, D)
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
