Question

我是班级工作的新手，更具体地说，是四叉树。我看了一个从here提取的四叉树的基本示例。

启动四叉树时，无法识别任何方法，我也不知道问题是源于原始代码还是因为我执行错误。

这是我从已经提到的网站复制的一些代码：


#Tree initialization
class QTree():

    def __init__(self, k, n): #Maximum number of points in a node (threshold) and points existing (n)

        self.treshold = k
        self.points = [Point(random.uniform(0, 10), random.uniform(0, 10)) for x in range(n)] #Generation of n points
        self.root = Node(0, 0, 10, 10, self.points)

    def add_point(x,y):
        return Point(x,y) 

    def get_points(self):

        return self.points

    def subdivide(self):

        recursive_subdivide(self.root,self.threshold)

    def graph(self):
        fig = plt.figure(figsize=(12, 8))
        plt.title("Quadtree")
        ax = fig.add_subplot(111)
        c = find_children(self.root)
        print "Number of segments: %d" %len(c)
        areas = set()
        for el in c:
            areas.add(el.width*el.height)
        for n in c:
            ax.add_patch(patches.Rectangle((n.x0, n.y0), n.width, n.height, 
        fill=False))
        x = [point.x for point in self.points]
        y = [point.y for point in self.points]
        plt.plot(x, y, 'ro')
        plt.show()

        return


     def recursive_subdivide(node,k):

        if len(node.points)<=k:
            return

        w_ = float(node.width/2)
        h_ = float(node.height/2)

        p = contains(node.x0, node.y0, w_, h_, node.points)
        x1 = Node(node.x0, node.y0, w_, h_, p ) #The new node (x1) will only contain the points that are within the node's limits
        recursive_subdivide(x1,k)

        p = contains(node.x0, node.y0+h_, w_, h_, node.points)
        x2 = Node(node.x0, node.y0+h_, w_, h_, p)
        recursive_subdivide(x2, k)

        p = contains(node.x0+w_, node.y0, w_, h_, node.points)
        x3 = Node(node.x0 + w_, node.y0, w_, h_, p)
        recursive_subdivide(x3, k)

        p = contains(node.x0+w_, node.y0+w_, w_, h_, node.points)
        x4 = Node(node.x0+w_, node.y0+h_, w_, h_, p)
        recursive_subdivide(x4, k)

        node.children = [x1, x2, x3, x4]


    def contains(x, y, w, h, points): #Select all the points that are inside the node´s limits
        pts = []
        for point in points:
            if point.x >= x and point.x <= x+w and point.y>=y and point.y<=y+h:
                pts.append(point)
                return pts

    def find_children(node):
        if not node.children:
            return [node]
        else:
            children = []
            for child in node.children:
                children += (find_children(child))
        return children

这样做之后：

q=QTree(3,200) #Threshold = 3, Number of points = 200
q.graph()

我总是遇到相同的错误： “ NameError：名称'find_children'未定义”。显然，启动Tree时没有一种方法可以识别。

可能是什么问题？我如何正确执行这样的树？

Quadtree中的方法无法识别-执行树时出错

0 个答案: