Do not copy for k_opt

tsp/tsp.py

@@ -1,7 +1,7 @@
 import math
 import time
 from functools import lru_cache
-from random import shuffle
+from random import shuffle, choice
 from map import Map
 
 
@@ -119,7 +119,8 @@ def swap_edges(i, j, points, current_distance=0):
     return current_distance
 
 
-def k_opt(p1, route, steps):
+def k_opt(p1, route):
+    steps = []
     ignore_set = set()
 
     for _ in range(10):
@@ -128,58 +129,58 @@ def k_opt(p1, route, steps):
         ignore_set.add(p2)
 
         p4 = None
-        # TODO(felixm): Keep track of current indices and then make this more efficient.
-        for p3 in route.points:
+        for p3, dist_p2p3 in p2.neighbors:
             if p3 is p2 or p3 is p1 or p3 in ignore_set:
                 continue
             p4_ = route.points[(p3.index - 1) % route.len_points]
             if p4_ in ignore_set or p4_ is p1:
                 continue
-
-            dist_p2p3 = distance(p2, p3)
-
+            # dist_p2p3 = distance(p2, p3)
             if dist_p2p3 < dist_p1p2:
                 dist_p1p2 = dist_p2p3
                 p4 = p4_
 
         if p4 is None:
-            return steps
+            break
 
         step = (p1.index, p4.index)
         new_total = route.swap(p1, p4)
         steps.append((new_total, step))
+
+
     return steps
 
 
 def local_search_k_opt(route):
     current_total = route.total_distance
-    ignore_set = set()
 
-    start_time = time.perf_counter()
-    while True:
-        # TODO(felixm): Get longest distance from heap in route.
-        point = longest_distance(route.points, ignore_set)
-        ignore_set.add(point)
+    no_improvement_iterations = 0
+    while no_improvement_iterations < 5:
+        no_improvement_iterations += 1
+        for point in list(route.points):
+            before_k_opt = current_total
+            steps = k_opt(point, route)
+            if not steps:
+                continue
 
-        if not point:
-            break
+            # Reverse route to status before k_opt. This is cheaper
+            # than copying the whole route and allows us to search
+            # the neighborhood faster.
+            for i in range(len(steps), 0, -1):
+                current_total = route.swap(*steps[i - 1][1])
+            assert(float_is_equal(before_k_opt, current_total))
 
-        if time.perf_counter() - start_time > 10:
-            return
+            new_total = min(steps, key=lambda t: t[0])[0]
+            if new_total < current_total:
+                for total, step in steps:
+                    p1, p4 = step
+                    current_total = route.swap(p1, p4)
+                    if total == new_total:
+                        break
+                assert(float_is_equal(route.total_distance, current_total))
 
-        copy_route = route.copy()
-        steps = k_opt(point, copy_route, [(current_total, None)])
-        new_total = min(steps, key=lambda t: t[0])[0]
-
-        if new_total < current_total:
-            # Skip first step as it is the original order.
-            for total, step in steps[1:]:
-                p1, p4 = step
-                current_total = route.swap(p1, p4)
-                if total == new_total:
-                    break
-            assert(float_is_equal(route.total_distance, current_total))
-            ignore_set = set()
+        # if no_improvement_iterations > 2:
+            # current_total = route.swap(choice(route.points), choice(route.points))
 
 
 class Route(object):
@@ -189,17 +190,6 @@ class Route(object):
         self.total_distance = self.get_total_distance(points)
         self.point_id_to_point = {p.id: p for p in self.points}
 
-    def copy(self):
-        route = Route([])
-        route.points = [p.copy() for p in self.points]
-        route.len_points = self.len_points
-        route.total_distance = self.total_distance
-        route.point_id_to_point = {p.id: p for p in route.points}
-        return route
-
-    def get_point(self, point):
-        return self.point_id_to_point[point.id]
-
     def verify_total_distance(self):
         a = self.total_distance
         b = self.get_total_distance(self.points)
@@ -234,6 +224,9 @@ class Route(object):
         if type(p2) is int:
             p2 = self.points[p2]
 
+        if p1 is p2:
+            return self.total_distance
+
         # Handle case when edge goes over the end of the list.
         p12 = self.points[(p1.index + 1) % self.len_points]
         p21 = self.points[(p2.index + 1) % self.len_points]
@@ -307,17 +300,18 @@ def solve_it(input_data):
     m = Map()
 
     m.cluster(r.points)
-    r.reorder_points_greedy()
+    # r.reorder_points_greedy()
     local_search_k_opt(r)
-    m.plot(r.points)
+    # m.plot(r.points)
 
     r.verify_total_distance()
     return prepare_output_data(r.points)
 
 
 if __name__ == "__main__":
-    file_location = "tsp/data/tsp_51_1"
-    # file_location = "tsp/data/tsp_6_1"
+    file_location = "data/tsp_51_1"
+    file_location = "data/tsp_200_2"
+    # file_location = "data/tsp_6_1"
     with open(file_location, 'r') as input_data_file:
         input_data = input_data_file.read()
         print(solve_it(input_data))