用matlab写一个A*算法，注释用中文

好的，以下是用 MATLAB 写的 A* 算法示例代码，并加上了中文注释：

function [path, cost] = a_star(start, goal, map)
% A* 算法实现
% Inputs:
%   start: 出发点坐标 [x,y]
%   goal: 目标点坐标 [x,y]
%   map: 环境地图，0 表示自由空间，1 表示障碍物
% Outputs:
%   path: 从出发点到目标点的路径，以 [x,y] 坐标的列表形式表示
%   cost: 路径的代价

% 定义启发式函数：欧几里得距离
heuristic = @(a,b) sqrt((a(1)-b(1))^2 + (a(2)-b(2))^2);

% 定义代价函数
cost_function = @(a,b) ((a(1)-b(1))^2 + (a(2)-b(2))^2);

% 初始化出发点
start_node.g_cost = 0;
start_node.h_cost = heuristic(start, goal);
start_node.f_cost = start_node.g_cost + start_node.h_cost;
start_node.coordinates = start;
start_node.parent = [];

% 初始化开放集合和关闭集合
open_set = [start_node];
closed_set = [];

% 循环直到到达目标点或无法到达
while ~isempty(open_set)
    % 找到 f_cost 值最小的节点
    current_node_idx = 1;
    current_node = open_set(current_node_idx);
    for i = 1:length(open_set)
        if open_set(i).f_cost < current_node.f_cost
            current_node_idx = i;
            current_node = open_set(current_node_idx);
        end
    end

    % 检查是否到达目标点
    if current_node.coordinates == goal
        path = [];
        cost = current_node.g_cost;
        while ~isempty(current_node.parent)
            path = [current_node.coordinates; path];
            current_node = current_node.parent;
        end
        path = [start; path];
        return
    end

    % 从开放集合中移除当前节点并将其添加到关闭集合中
    open_set(current_node_idx) = [];
    closed_set = [closed_set; current_node];

    % 找到当前节点的邻居节点
    [neighbors_x, neighbors_y] = find(neighbors(map, current_node.coordinates));
    neighbors = [neighbors_x, neighbors_y];

    % 循环遍历每个邻居节点
    for i = 1:length(neighbors)
        neighbor_node.coordinates = neighbors(i,:);
        neighbor_node.g_cost = current_node.g_cost + cost_function(current_node.coordinates, neighbor_node.coordinates);
        neighbor_node.h_cost = heuristic(neighbor_node.coordinates, goal);
        neighbor_node.f_cost = neighbor_node.g_cost + neighbor_node.h_cost;
        neighbor_node.parent = current_node;

        % 检查邻居节点是否已经在关闭集合中
        if any(ismember(closed_set, neighbor_node.coordinates, 'rows'))
            continue
        end

        % 检查邻居节点是否已经在开放集合中
        neighbor_idx = find(ismember(open_set, neighbor_node.coordinates, 'rows'));
        if ~isempty(neighbor_idx)
            % 检查到达邻居节点的新路径是否更优
            if neighbor_node.g_cost < open_set(neighbor_idx).g_cost
                open_set(neighbor_idx) = neighbor_node;
            end
        else
            % 将邻居节点添加到开放集合中
            open_set = [open_set; neighbor_node];
        end
    end
end

% 如果无法到达目标点
path = [];
cost = inf;

end


function [neighborhood] = neighbors(map, coordinates)
% 返回以给定坐标为中心的 3x3 邻域
neighborhood = map(coordinates(1)-1:coordinates(1)+1, coordinates(2)-1:coordinates(2)+1);
end

希望这份代码对你有所帮助！