R/sweep_for_forecast_towns.R

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

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

sweep_for_forecast_towns <- function(latlon = c(-35.3, 149.2)) {
  Lat <- latlon[1]
  Lon <- latlon[2]

  # CRAN NOTE avoidance:
  AAC_codes <- lat <- lon <- NULL # nocov

  # Load JSON URL list
  load(system.file("extdata",
                   "AAC_codes.rda",
                   package = "bomrang"))

  AAC_codes %>%
    copy %>%
    # Lat Lon are in JSON
    .[, "distance" := .haversine_distance(Lat, Lon, lat, lon)] %>%
    setorderv("distance") %>%
    .[]
}