R/sweep_for_stations.R

In adamhsparks/BOMRang: Australian Government Bureau of Meteorology ('BOM') Data Client

#' Find nearest BOM weather stations
#'
#' @param latlon A length-2 numeric vector. By default, Canberra
#' (approximately).
#' @return A \code{\link{data.table}} of all weather stations (in this package)
#' sorted by distance from \var{latlon}, ascending.
#' @author Hugh Parsonage, \email{hugh.parsonage@@gmail.com}
#' @importFrom data.table copy setorderv
#' @export sweep_for_stations

sweep_for_stations <- function(latlon = c(-35.3, 149.2)) {
  Lat <- latlon[1]
  Lon <- latlon[2]
  
  if (!identical(length(latlon), 2L) ||
      !is.numeric(latlon)) {
    stop("latlon must be a 2-element numeric vector.",
         call. = FALSE)
  }
  
  # CRAN NOTE avoidance:
  JSONurl_site_list <- lat <- lon <- NULL # nocov
  
  # Load JSON URL list
  load(system.file("extdata",
                   "JSONurl_site_list.rda",
                   package = "bomrang"))
  
  JSONurl_site_list %>%
    copy %>%
    # Lat Lon are in JSON
    .[, "distance" := .haversine_distance(Lat, Lon, lat, lon)] %>%
    setorderv("distance") %>%
    .[]
}