显示经度/纬度点的子集？ [英] Displaying a subset of longitude/latitude points?

问题描述

我以这种方式制作了一组坐标（纬度和经度）：

I have an array of coordinates (latitude and longitude) maded in this way:

[0] = "45.01234,9.12345"
[1] = "46.11111,9.12345"
[2] = "47.22222,9.98765"
[...] etc

在一个循环中，将这些坐标转换为米（UTM北移/ UTM东移），然后将这些坐标转换为屏幕上的像素（X / Y）（输出设备是iPhone）在自定义地图上绘制路线。

In a loop, convert these coordinates in meters (UTM northing / UTM easting) and after that I convert these coords in pixel (X / Y) on screen (the output device is an iPhone) to draw a route line on a custom map.

[0] = "512335.00000,502333.666666"
[...] etc

返回的像素将传递到在屏幕上绘制线的方法（模拟路线计算）。

The returning pixel are passed to a method that draw a line on screen (simulating a route calculation).

[0] = "20,30"
[1] = "21,31"
[2] = "25,40"
[...] etc

作为坐标（纬度/经度）也是很多，我需要截断纬度/经度数组，以消除未填入地图范围（屏幕上地图的可见部分）的值。

地图范围是2对经纬度坐标，左上和右下。

As coordinate (lat/lon) are too many, I need to truncate lat/lon array eliminating the values that doesn't fill in the map bound (the visible part of map on screen).
Map bounds are 2 couple of coords lat/lon, upper left, and lower right.

现在，在此数组上循环的最佳方法是什么（未排序），并检查值是否在范围内，并在除去外部值之后？

要返回只包含屏幕上可见坐标的干净数组吗？

Now, what is the best way to loop on this array (NOT SORTED) and check if a value is or not in bound and after remove the value that is outside?
To return a clean array that contains only the coords visible on screen?

注意：coords数组是一个很大的数组。 4000/5000个项目。

此方法应在每次拖动或缩放时循环播放。

Note: the coords array is a very big array. 4000/5000 Couple of items.
This is a method that should be looped every drag or zoom.

如何在以下位置优化搜索和控件这个数组？

How can I optimize search and controls in this array?

推荐答案

我建议将其分为几个步骤：

I'd suggest breaking this into several steps:

1. 在新坐标系中将每个经度/纬度对转换为米。


2. 创建一个包含所有点的kd-tree数据结构集合。这样，您就可以非常有效地查询位于给定矩形范围内的点。


3. 每当视口发生变化时，请在kd树中找到将在该矩形中显示的所有点。 / li>
   
4. 要显示点，请遍历要显示的点集并显示每个点。

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