r - 无法使用Haversine公式正确使用R中的纬度和经度计算距离

Question

geolocation = function(long1, lat1, long2, lat2){
  R = 6371 #Mean radius of the earth in km
  diff.long = (long2-long1)
  diff.lat = (lat2-lat1)
  print(diff.lat)
  a =(sin(diff.lat/2) * sin(diff.lat/2) + cos(lat1) * cos(lat2) * sin(diff.long/2)* sin(diff.long/2))
  c= 2*atan2(sqrt(a),sqrt(1-a))
  d = R*c
  print(d)

  return(d) #Distance in km

}

当我使用如下传递的值运行它时，它返回 60.0719 而值为 1.030764

x= 地理位置(-73.84431, 40.72132, -73.84161, 40.71228)
打印(x)

我是 R 的新手，所以如果我在代码中犯了任何愚蠢的错误，请原谅

Answer 1

对于此公式，您需要将度数转换为弧度。

创建一个附加函数:

deg2rad <- function(deg) return(deg*pi/180)

并在您的 geolocation 中使用此转换功能:

geolocation = function(long1, lat1, long2, lat2){

  # Convert degrees to radians
  long1 <- deg2rad(long1)
  lat1 <- deg2rad(lat1)
  long2 <- deg2rad(long2)
  lat2 <- deg2rad(lat2)

  R = 6371 #Mean radius of the earth in km

  diff.long = (long2-long1)
  diff.lat = (lat2-lat1)

  a =(sin(diff.lat/2) * sin(diff.lat/2) + cos(lat1) * cos(lat2) * sin(diff.long/2)* sin(diff.long/2))
  c= 2*atan2(sqrt(a),sqrt(1-a))
  d = R*c

  return(d) #Distance in km
}

你应该得到:

geolocation(-73.84431, 40.72132, -73.84161 , 40.71228)
[1] 1.030637

或者，考虑 geosphere可以进行类似计算的可用函数包。