R/monitor_distance.R

In PWFSLSmoke: Utilities for Working with Air Quality Monitoring Data

#' @keywords ws_monitor
#' @export
#' @title Calculate distances from monitors to a location of interest
#' @param ws_monitor \emph{ws_monitor} object
#' @param longitude longitude of the location of interest
#' @param latitude latitude of the location of interest
#' @description This function returns the distances (km) between monitoring
#' sites and a location of interest. These distances can be used to create a
#' mask identifying monitors within a certain radius of the location of interest.
#' @return Vector of of distances (km).
#' @seealso \code{\link{distance}}
#' @examples
#' library(PWFSLSmoke)
#'
#' N_M <- Northwest_Megafires
#' # Walla Walla
#' WW_lon <- -118.330278
#' WW_lat <- 46.065
#' distance <- monitor_distance(N_M, WW_lon, WW_lat)
#' closestIndex <- which(distance == min(distance))
#' distance[closestIndex]
#' N_M$meta[closestIndex,]

monitor_distance <- function(ws_monitor, longitude, latitude) {

  # Sanity check
  if ( monitor_isEmpty(ws_monitor) )
    stop("ws_monitor object contains zero monitors")

  distance <- distance(longitude, latitude,
                       ws_monitor$meta$longitude, ws_monitor$meta$latitude)
  names(distance) <- ws_monitor$meta$monitorID

  return(distance)

}