Question

我正在编写一个具有大量位置的应用程序，所有位置都有坐标，我希望应用程序能够按名称搜索位置，或者哪个位置最接近。我知道如何通过半正弦公式确定两个坐标之间的距离。但是，我希望我的应用程序遍历数组中的每个对象（位置），并向该对象添加一个名为distance的新元素，distance应该是距我所在位置的距离。我有以下代码，我认为应该有效，但事实并非如此。有没有人有任何想法？

function GetLocation(location) {
    myLat = location.coords.latitude;
    myLon = location.coords.longitude;
    angular.forEach($scope.ASiteLocs, function(object, location) {
      location.Point.coordinates = location.Point.coordinates.substring(0, clength - 2).split(",");
      Lat = location.Point.coordinates[0];
      Lon = location.Point.coordinates[1];
      function getCoordDistance() {
        Number.prototype.toRad = function() {
          return this * Math.PI / 180;
        }

        var lat2 = myLat;
        var lon2 = myLon;
        var lat1 = Lat;
        var lon1 = Lon;

        var R = 3959; // Radius in miles 
        //has a problem with the .toRad() method below.
        var x1 = lat2 - lat1;
        var dLat = x1.toRad();
        var x2 = lon2 - lon1;
        var dLon = x2.toRad();
        var a = Math.sin(dLat / 2) * Math.sin(dLat / 2) +
          Math.cos(lat1.toRad()) * Math.cos(lat2.toRad()) *
          Math.sin(dLon / 2) * Math.sin(dLon / 2);
        var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
        var d = R * c;

      }
      object.distance = d;
    });
  }

以下是地点的样子（只是其中几个）：

"name": "502 Nelson St, Greenville, MS 38701",
    "visibility": "0",
    "description": "502 Nelson St, Greenville, MS 38701",
    "styleUrl": "#waypoint",
    "Point": {
      "coordinates": "-91.05636,33.415485,0"
    }
  }, {
    "name": "242 Blackhawk Trace, Galena, IL 61036",
    "visibility": "0",
    "description": "242 Blackhawk Trace, Galena, IL 61036",
    "styleUrl": "#waypoint",
    "Point": {
      "coordinates": "-90.319778,42.390862,0"
    }
  }, {
    "name": "3747 Ocean Dr, Vero Beach, FL 32963",
    "visibility": "0",
    "description": "3747 Ocean Dr, Vero Beach, FL 32963",
    "styleUrl": "#waypoint",
    "Point": {
      "coordinates": "-80.358248,27.659094,0"
    }
  }

如果这样可以更容易阅读，那么这是我的工作内容。
http://plnkr.co/edit/nRQc7Ym0lsaK6jQwd626?p=preview

Answer 1

将angular.forEach用于对象数组时，函数的第一个参数是对象，第二个是数组索引：

angular.forEach($scope.ASiteLocs, function(location, arrayIndex) {
    ...
    location.distance = d;
})

注意1：您正在更改forEach中的location.Point.coordinates从字符串到数组，因此GetLocation函数只能工作一次，因为原始位置数组已更改。

注意2：在循环中定义一个函数是不好的做法而且很昂贵＆＃39;

Answer 2

如果您在代码中使用我的npm包haversine-calculator，您的代码会更清晰：

const haversineCalculator = require('haversine-calculator')

const start = {
  latitude: -23.754842,
  longitude: -46.676781
}

const end = {
  latitude: -23.549588,
  longitude: -46.693210
}

console.log(haversineCalculator(start, end))
console.log(haversineCalculator(start, end, {unit: 'meter'}))
console.log(haversineCalculator(start, end, {unit: 'mile'}))
console.log(haversineCalculator(start, end, {threshold: 1}))
console.log(haversineCalculator(start, end, {threshold: 1, unit: 'meter'}))
console.log(haversineCalculator(start, end, {threshold: 1, unit: 'mile'}))

AngularJS获取多个坐标之间的距离

2 个答案: