R/dtHaversine.R

In BrianAronson/docshop: Doctor Shopping Functions

#' Calculate Haversine distance using data.table framework
#' @export

dtHaversine <-
  function(lat_from, lon_from, lat_to, lon_to, r = 6378137) {
    radians <- pi / 180
    lat_to <- lat_to * radians
    lat_from <- lat_from * radians
    lon_to <- lon_to * radians
    lon_from <- lon_from * radians
    dLat <- (lat_to - lat_from)
    dLon <- (lon_to - lon_from)
    a <-(sin(dLat / 2) ^ 2) + (cos(lat_from) * cos(lat_to)) * (sin(dLon / 2) ^2)
    return(2 * atan2(sqrt(a), sqrt(1 - a)) * r)
  }