对 lonlat 点的排序列表，从最近的开始-移动开发问题

Sort list of lonlat points, start with nearest(对 lonlat 点的排序列表，从最近的开始)

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问题描述

我有来自 GPS 的位置(lon_base、lat_base).我有一个位置列表(lon1、lat1|lon2、lat2|lon3、lat3...)这个列表很长，遍布世界各地.

I have location from GPS (lon_base, lat_base). I have a list of locations (lon1, lat1|lon2, lat2|lon3, lat3...) This list is very long and is around the world.

我的问题是:1. 如何从该列表中仅获取距离我的 lon_baselat_base 1 英里的 lonlat?2. 如何从近到远排序?

My questions are: 1. How do I get from that list only the lonlat that are 1 mile from my lon_baselat_base? 2. How do I sort them from closest to farthest?

提前致谢！

推荐答案

你想定义你自己的 Comparator，一般看起来像这样:

You want to define your own Comparator that, in general, looks something like this:

LonLat myHouse = /* whatever */ ;
Comparable comp = new Comparable () {
    LonLat a;
    int compareTo (Object b) {
        int aDist = calcDistance(a, myHouse) ;
        int bDist = calcDistance(b, myHouse) ;
        return aDist - bDist;
    }
};
myLonLatList.sort(lonLatList, comp);

其中 calcDistance() 只是计算两点之间的距离.如果您使用的是 Android，我认为 Google Maps 在其 API 中的某处有一个功能可以为您执行此操作.

where calcDistance() simply calculates the distance between the two points. If you're on Android, I think Google Maps has a function somewhere in their API that will do this for you.

EDIT:你会希望你的 calcDistance() 函数看起来像 ChrisJ 的 distance 函数.

EDIT : You'll want your calcDistance() function to look like ChrisJ's distance function.

-tjw

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