Question

我一直在开发一个天然气站公司的roid申请。申请使用权图。

The user selects two points on the map and i show the route between selected points. The application needs to show nearest(in 2 miles radius) gas stations on the selected route.

The route is a coordinate array like: Route[5000] = {"lon1,lat1","lon2,lat2","lon3,lat3","lon4,lat5"... }

And i have a gas stations list which consists of coordinates. GasStations[200] = {"lon1,lat1","lon2,lat2","lon3,lat3","lon4,lat5"... }

您可以建议我计算路线上最接近的天然气站的高性能算法。

感谢。

Answer 1

我不熟悉甲状腺。此处,C#方法计算两个楼梯之间的距离。如果距离在2英里半径之内,则该站就座。

是的,你将不得不通过5000x200 = 1 000 000 000,但速度相当快。

我希望这将有助于。

decimal distance = CalculateDistance(stationLatitude, stationLongitude, routeLatitude, routeLongitude);

private static double ToRadian(double val)
{
    return (Math.PI / 180) * val;
}

private static double ToXAxis(decimal lat, decimal lng)
{
    return (Math.Cos(4 * (4 * Math.Atan2(1, 5) - Math.Atan2(1, 239)) / 180 * (double)lat) *
        Math.Cos(4 * (4 * Math.Atan2(1, 5) - Math.Atan2(1, 239)) / 180 * (double)lng));
}

private static double ToYAxis(decimal lat, decimal lng)
{
    return (Math.Cos(4 * (4 * Math.Atan2(1, 5) - Math.Atan2(1, 239)) / 180 * (double)lat) *
        Math.Sin(4 * (4 * Math.Atan2(1, 5) - Math.Atan2(1, 239)) / 180 * (double)lng));
}

private static double ToZAxis(decimal lat)
{
    return Math.Sin(4 * (4 * Math.Atan2(1, 5) - Math.Atan2(1, 239)) / 180 * (double)lat);
}

private static decimal CalculateDistance(decimal lat1, decimal lng1, decimal lat2, decimal lng2)
{
    double cntXAxis = Math.Cos(ToRadian((double) lat1))*Math.Cos(ToRadian((double) lng1));
    double cntYAxis = Math.Cos(ToRadian((double) lat1))*Math.Sin(ToRadian((double) lng1));
    double cntZAxis = Math.Sin(ToRadian((double) lat1));

    return (decimal) (3961*Math.Acos(ToXAxis(lat2, lng2)*cntXAxis + ToYAxis(lat2, lng2)*cntYAxis + ToZAxis(lat2)*cntZAxis));
}

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