Bug fixes when save_best_solutions=True

Some bug fixes when setting the save_best_solutions parameter to True. Previously, the best solution for generation i was added into the best_solutions attribute at generation i+1. Now, the best_solutions attribute is updated by each solution at its exact generation.

Author: ahmedfgad

__init__.py

@@ -1,3 +1,3 @@
 from .pygad import * # Relative import.
 
-__version__ = "2.14.2"
+__version__ = "2.14.3"

pygad.py

@@ -937,19 +937,19 @@ def run(self):
         # Measuring the fitness of each chromosome in the population. Save the fitness in the last_generation_fitness attribute.
         self.last_generation_fitness = self.cal_pop_fitness()
 
+        best_solution, best_solution_fitness, best_match_idx = self.best_solution(pop_fitness=self.last_generation_fitness)
+
+        # Appending the best solution in the initial population to the best_solutions list.
+        if self.save_best_solutions:
+            self.best_solutions.append(best_solution)
+
         for generation in range(self.num_generations):
             if not (self.on_fitness is None):
                 self.on_fitness(self, self.last_generation_fitness)
 
-            best_solution, best_solution_fitness, best_match_idx = self.best_solution(pop_fitness=self.last_generation_fitness)
-
             # Appending the fitness value of the best solution in the current generation to the best_solutions_fitness attribute.
             self.best_solutions_fitness.append(best_solution_fitness)
 
-            # Appending the best solution to the best_solutions list.
-            if self.save_best_solutions:
-                self.best_solutions.append(best_solution)
-
             # Selecting the best parents in the population for mating.
             self.last_generation_parents = self.select_parents(self.last_generation_fitness, num_parents=self.num_parents_mating)
             if not (self.on_parents is None):
@@ -993,6 +993,12 @@ def run(self):
             # Measuring the fitness of each chromosome in the population. Save the fitness in the last_generation_fitness attribute.
             self.last_generation_fitness = self.cal_pop_fitness()
 
+            best_solution, best_solution_fitness, best_match_idx = self.best_solution(pop_fitness=self.last_generation_fitness)
+
+            # Appending the best solution to the best_solutions list.
+            if self.save_best_solutions:
+                self.best_solutions.append(best_solution)
+
             # If the callback_generation attribute is not None, then cal the callback function after the generation.
             if not (self.on_generation is None):
                 r = self.on_generation(self)