R/bearing.R

In lawn: Client for 'Turfjs' for 'Geospatial' Analysis

#' Get geographic bearing between two points
#'
#' Takes two [data-Point]'s and finds the geographic bearing
#' between them.
#'
#' @export
#' @param start Starting [data-Feature] with a single [data-Point]
#' @param end Ending [data-Feature] with a single [data-Point]
#' @template lint
#' @family measurements
#' @return A numeric value of the bearing in degrees.
#' @examples
#' start <- '{
#'  "type": "Feature",
#'  "properties": {
#'    "marker-color": "#f00"
#'  },
#'  "geometry": {
#'    "type": "Point",
#'    "coordinates": [-75.343, 39.984]
#'  }
#' }'
#'
#' end <- '{
#'   "type": "Feature",
#'   "properties": {
#'     "marker-color": "#0f0"
#'   },
#'   "geometry": {
#'     "type": "Point",
#'     "coordinates": [-75.534, 39.123]
#'   }
#' }'
#' lawn_bearing(start, end)
lawn_bearing <- function(start, end, lint = FALSE) {
  start <- convert(start)
  end <- convert(end)
  lawnlint(list(start, end), lint)
  if (lint) {
    is_type(start, type_top = "Feature", type_lower = "Point")
    is_type(end, type_top = "Feature", type_lower = "Point")
  }
  ct$eval(sprintf("var bear = turf.bearing(%s, %s);", start, end))
  ct$get("bear")
}