存储用于通过x，y坐标定位的对象

I'm trying to determine a fast way of storing a set of objects, each of which have an x and y coordinate value, such that I can quickly retrieve all objects within a certain rectangle or circle. For small sets of objects (~100) the naive approach of simply storing them in a list, and iterating through it, is relatively quick. However, for much larger groups, that is expectedly slow. I've tried storing them in a pair of TreeMaps as well, one sorted on the x coordinate, and one sorted on the y coordinate, using this code:

我正在尝试确定一种存储一组对象的快速方法,每个对象都有一个x和y坐标值,这样我就可以快速检索某个矩形或圆形内的所有对象。对于小型对象集(~100),简单地将它们存储在列表中并通过它迭代的简单方法相对较快。但是,对于规模更大的群体来说,这预计会很慢。我已经尝试将它们存储在一对TreeMaps中,一个在x坐标上排序,一个在y坐标上排序,使用以下代码:

xSubset = objectsByX.subSet( minX, maxX );
ySubset = objectsByY.subSet( minY, maxY );
result.addAll( xSubset );
result.retainAll( ySubset );

This also works, and is faster for larger sets of objects, but is still slower than I would like. Part of the problem is also that these objects move around, and need to be inserted back into this storage, which means removing them from and re-adding them to the trees/lists. I can't help but think there must be better solutions out there. I'm implementing this in Java, if it makes any difference, though I expect any solution will be more in the form of a useful pattern/algorithm.

这也适用,对于较大的对象集更快,但仍然比我想要的慢。部分问题还在于这些对象移动,需要插回到此存储中,这意味着将它们从树中删除并重新添加到树/列表中。我不禁想到那里必须有更好的解决方案。我在Java中实现这个,如果它有任何区别,尽管我希望任何解决方案都会以有用的模式/算法的形式出现。

6 个解决方案

#1

Quadtrees seem to solve the specific problem I asked. Kd-Trees are a more general form, for any number of dimensions, rather than just two.

Quadtrees似乎解决了我问的具体问题。 Kd-Trees是一种更通用的形式,适用于任何数量的维度,而不仅仅是两个维度。

R-Trees may also be useful if the objects being stored have a bounding rectangle, rather than being just a simple point.

如果存储的对象具有边界矩形,而不仅仅是一个简单的点,则R树也可能很有用。

The general term for these type of structures is Spatial Index.

这些类型结构的总称是空间索引。

There is a Java implementation of Quadtree and R-Tree.

有一个Quachiree和R-Tree的Java实现。

#2

The general term is a Spatial Index. I guess you should choose according to the existing implementations.

一般术语是空间索引。我想你应该根据现有的实现来选择。

#3

A quadtree is the structure which is usually used for that.

四叉树是通常用于此的结构。

#4

Have a look at Kd-Trees.

看看Kd-Trees。

#5

Simple QuadTree implementation in C# (easy to translate into java) http://www.codeproject.com/KB/recipes/QuadTree.aspx

C#中简单的QuadTree实现(易于翻译成java)http://www.codeproject.com/KB/recipes/QuadTree.aspx

#6

You could put all the x cords in a map, and the y cords in another map, and have the map values point to the object.

您可以将所有x条线放在地图中,将y绳索放在另一个地图中,并使地图值指向该对象。

        TreeMap<Integer, TreeMap<Integer, Point>> xMap = new TreeMap<Integer, TreeMap<Integer, Point>>();
        for (int x = 1; x < 100; x += 2)
            for (int y = 0; y < 100; y += 2)
                {
                    Point p = new Point(x, y);
                    TreeMap<Integer, Point> tempx = xMap.get(x);
                    if (tempx == null)
                        {
                            tempx = new TreeMap<Integer, Point>();
                            xMap.put(x, tempx);
                        }
                    tempx.put(y, p);
                }
        SortedMap<Integer, TreeMap<Integer, Point>> tempq = xMap.subMap(5, 8);
        Collection<Point> result = new HashSet<Point>();
        for (TreeMap<Integer, Point> smaller : tempq.values())
            {
                SortedMap<Integer, Point> smallerYet = smaller.subMap(6, 12);
                result.addAll(smallerYet.values());
            }
        for (Point q : result)
            {
                System.out.println(q);
            }
    }

#1