From 7dd68707124da17bc0de801de4c690be515926ab Mon Sep 17 00:00:00 2001
From: JonZhao <1044264932@qq.com>
Date: Tue, 28 May 2019 21:19:08 +0800
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---
 basic_aco.py | 142 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 142 insertions(+)
 create mode 100644 basic_aco.py

(limited to 'basic_aco.py')

diff --git a/basic_aco.py b/basic_aco.py
new file mode 100644
index 0000000..3bdc24c
--- /dev/null
+++ b/basic_aco.py
@@ -0,0 +1,142 @@
+import numpy as np
+import random
+from vprtw_aco_figure import VrptwAcoFigure
+from vrptw_base import VrptwGraph, PathMessage
+from ant import Ant
+from threading import Thread
+from queue import Queue
+
+
+class BasicACO:
+    def __init__(self, graph: VrptwGraph, ants_num=10, max_iter=200, alpha=1, beta=2):
+        super()
+        # graph 结点的位置、服务时间信息
+        self.graph = graph
+        # ants_num 蚂蚁数量
+        self.ants_num = ants_num
+        # max_iter 最大迭代次数
+        self.max_iter = max_iter
+        # vehicle_capacity 表示每辆车的最大载重
+        self.max_load = graph.vehicle_capacity
+        # 信息素强度
+        self.Q = 1
+        # alpha 信息素信息重要新
+        self.alpha = alpha
+        # beta 启发性信息重要性
+        self.beta = beta
+        # q0 表示直接选择概率最大的下一点的概率
+        self.q0 = 0.1
+        # best path
+        self.best_path_distance = None
+        self.best_path = None
+        self.best_vehicle_num = None
+
+        self.whether_or_not_to_show_figure = True
+
+    def run_basic_aco(self):
+        # 开启一个线程来跑_basic_aco，使用主线程来绘图
+        path_queue_for_figure = Queue()
+        basic_aco_thread = Thread(target=self._basic_aco, args=(path_queue_for_figure,))
+        basic_aco_thread.start()
+
+        # 是否要展示figure
+        if self.whether_or_not_to_show_figure:
+            figure = VrptwAcoFigure(self.graph, path_queue_for_figure)
+            figure.run()
+        basic_aco_thread.join()
+
+        # 传入None作为结束标志
+        if self.whether_or_not_to_show_figure:
+            path_queue_for_figure.put(PathMessage(None, None))
+
+    def _basic_aco(self, path_queue_for_figure: Queue):
+        """
+        最基本的蚁群算法
+        :return:
+        """
+        # 最大迭代次数
+        for iter in range(self.max_iter):
+
+            # 为每只蚂蚁设置当前车辆负载，当前旅行距离，当前时间
+            ants = list(Ant(self.graph) for _ in range(self.ants_num))
+            for k in range(self.ants_num):
+
+                # 蚂蚁需要访问完所有的客户
+                while not ants[k].index_to_visit_empty():
+                    next_index = self.select_next_index(ants[k])
+                    # 判断加入该位置后，是否还满足约束条件, 如果不满足，则再选择一次，然后再进行判断
+                    if not ants[k].check_condition(next_index):
+                        next_index = self.select_next_index(ants[k])
+                        if not ants[k].check_condition(next_index):
+                            next_index = 0
+
+                    # 更新蚂蚁路径
+                    ants[k].move_to_next_index(next_index)
+                    self.graph.local_update_pheromone(ants[k].current_index, next_index)
+
+                # 最终回到0位置
+                ants[k].move_to_next_index(0)
+                self.graph.local_update_pheromone(ants[k].current_index, 0)
+
+            # 计算所有蚂蚁的路径长度
+            paths_distance = np.array([ant.total_travel_distance for ant in ants])
+
+            # 记录当前的最佳路径
+            best_index = np.argmin(paths_distance)
+            if self.best_path is None:
+                self.best_path = ants[int(best_index)].travel_path
+                self.best_path_distance = paths_distance[best_index]
+                if self.whether_or_not_to_show_figure:
+                    path_queue_for_figure.put(PathMessage(self.best_path, self.best_path_distance))
+
+            elif paths_distance[best_index] < self.best_path_distance:
+                self.best_path = ants[int(best_index)].travel_path
+                self.best_path_distance = paths_distance[best_index]
+                if self.whether_or_not_to_show_figure:
+                    path_queue_for_figure.put(PathMessage(self.best_path, self.best_path_distance))
+
+            print('[iteration %d]: best distance %f' % (iter, self.best_path_distance))
+            # 更新信息素表
+            self.graph.global_update_pheromone(self.best_path, self.best_path_distance)
+
+    def select_next_index(self, ant):
+        """
+        选择下一个结点
+        :param ant:
+        :return:
+        """
+        current_index = ant.current_index
+        index_to_visit = ant.index_to_visit
+
+        transition_prob = np.power(self.graph.pheromone_mat[current_index][index_to_visit], self.alpha) * \
+            np.power(self.graph.heuristic_info_mat[current_index][index_to_visit], self.beta)
+
+        if np.random.rand() < self.q0:
+            max_prob_index = np.argmax(transition_prob)
+            next_index = index_to_visit[max_prob_index]
+        else:
+            # 使用轮盘赌算法
+            next_index = BasicACO.stochastic_accept(index_to_visit, transition_prob)
+        return next_index
+
+    @staticmethod
+    def stochastic_accept(index_to_visit, transition_prob):
+        """
+        轮盘赌
+        :param index_to_visit: a list of N index (list or tuple)
+        :param transition_prob:
+        :return: selected index
+        """
+        # calculate N and max fitness value
+        N = len(index_to_visit)
+
+        # normalize
+        sum_tran_prob = np.sum(transition_prob)
+        norm_transition_prob = transition_prob/sum_tran_prob
+
+        # select: O(1)
+        while True:
+            # randomly select an individual with uniform probability
+            ind = int(N * random.random())
+            if random.random() <= norm_transition_prob[ind]:
+                return index_to_visit[ind]
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