如何将纬度和经度转换为北、南、东、西。 如果可能在 javascript 中？

Question

let latitude: = 36.6839559;
let longitude = 3.6217802;

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此 API 需要北、南、东、西参数

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const API = `http://api.geonames.org/citiesJSON?north=${north}south=${south}&east=${east}&west=${west}&lang=de&username=demo`;

Answer 1

如果longitude < 0则为West ，否则为East 。

如果latitude < 0则为South ，否则为North 。

Answer 2

好吧，这个 api 似乎使用了边界框。 北，东，南和西是盒子的角落。 与其他答案相反，仅输出坐标是行不通的。 您需要所有的边界坐标。

因此，要将坐标转换为北、东等，我们应该加或减一公里（这已经足够近了）。 这是在 function kmInDegree(lat,long)中计算的。 计算是根据此处找到的函数完成的。

因此，如果我们取阿尔及利亚的 Beni Amrane (36.68395,3.6217802) 并添加和减去正确的值，我们会得到这个边界框：

如果我们然后将这些值传递给 url 我们得到以下 output

const API = 'http://api.geonames.org/citiesJSON?north=36.69395&south=36.67395&east=3.6324802&west=3.6104802&lang=de&username=demo';

//Result of the api call above
{
    "geonames": [
        {
            "lng": 3.616667,
            "geonameId": 2507983,
            "countrycode": "DZ",
            "name": "’Aïn N’Sara",
            "fclName": "city, village,...",
            "toponymName": "’Aïn N’Sara",
            "fcodeName": "populated place",
            "wikipedia": "",
            "lat": 36.683333,
            "fcl": "P",
            "population": 0,
            "fcode": "PPL"
        }
    ]
}

可以使用以下 function 自动执行此过程：

 function getBox(lat, long) { //calculate the offset of 1km at a certain coordinate const dist = kmInDegree(lat, long) //calculate the bounds and make an object of them let bounds = { north: lat + dist.lat, south: lat - dist.lat, east: long + dist.long, west: long - dist.long }; return bounds; } //See https://en.wikipedia.org/wiki/Latitude#Length_of_a_degree_of_latitude function kmInDegree(lat, long) { const pi = Math.PI; const eSq = 0.00669437999014; const a = 6378137.0; //equatorial radius in metres lat = lat * pi / 180; //convert to radians long = long * pi / 180; //convert radians //I won't try to explain the calculations. All i know is that they are correct with the examples on wikipedia (see url above) const latLength = (pi * a * (1 - eSq)) / (180 * Math.pow((1 - eSq * Math.pow(Math.sin(lat), 2)), 3 / 2)); const longLength = (pi * a * Math.cos(long)) / (180 * Math.sqrt((1 - (eSq * Math.pow(Math.sin(long), 2))))); //If you want a greater offset, say 5km then change 1000 into 5000 return { lat: 1000 / latLength, long: 1000 / longLength }; } //Just for demonstration purposes only. window.onload = function() { //get the box from the coordinates let box = getBox(36.68395, 3.6217802); //create the API URL const API = `http:\/\/api.geonames.org/citiesJSON?north=${box.north}&south=${box.south}&east=${box.east}&west=${box.west}&lang=de&username=demo`; console.log(API); }

希望对你有帮助，如果没有，请评论