utils

src/utils.py

@@ -1,3 +1,53 @@
+import numpy as np
+
+def compute_lenght(solution, dist_matrix):
+    total_length = 0
+    starting_node = solution[0]
+    from_node = starting_node
+    for node in solution[1:]:
+        total_length += dist_matrix[from_node, node]
+        from_node = node
+    return total_length
+
+
+class random_initialier:
+    @staticmethod
+    def random_method(instance_):
+        n = int(instance_.nPoints)
+        solution = np.random.choice(np.arange(n), size=n, replace=False)
+        return np.concatenate([solution, [solution[0]]])
+
+
+class nearest_neighbor:
+    @staticmethod
+    def nn(instance_, starting_node=0):
+        dist_matrix = np.copy(instance_.dist_matrix)
+        n = int(instance_.nPoints)
+        node = starting_node
+        tour = [node]
+        for _ in range(n - 1):
+            for new_node in np.argsort(dist_matrix[node]):
+                if new_node not in tour:
+                    tour.append(new_node)
+                    node = new_node
+                    break
+        tour.append(starting_node)
+        return np.array(tour)
+
+    @staticmethod
+    def best_nn(self, instance_):
+        solutions, lens = [], []
+        for start in range(self.instance.nPoints):
+            new_solution = self.nn(instance_, starting_node=start)
+            solutions.append(new_solution)
+            assert self.check_if_solution_is_valid(new_solution), "error on best_nn method"
+            lens.append(self.evaluate_solution(return_value=True))
+
+        self.solution = solutions[np.argmin(lens)]
+        self.solved = True
+        return self.solution
+
+
 class multi_fragment:
 
     @staticmethod
@@ -63,12 +113,3 @@ class multi_fragment:
         sol_list.append(n1)
         return sol_list
 
-
-def compute_lenght(solution, dist_matrix):
-    total_length = 0
-    starting_node = solution[0]
-    from_node = starting_node
-    for node in solution[1:]:
-        total_length += dist_matrix[from_node, node]
-        from_node = node
-    return total_length