R/monitor_map.R

In PWFSLSmoke: Utilities for Working with Air Quality Monitoring Data

#' @keywords ws_monitor
#' @export
#' @import maps mapproj
#'
#' @title Static map of monitoring stations
#'
#' @param ws_monitor \emph{ws_monitor} object
#' @param slice either a time index or a function used to collapse the time axis
#' @param breaks set of breaks used to assign colors
#' @param colors set of colors must be one less than the number of breaks
#' @param pch Plot symbols used to draw points on the map.
#' @param cex the amount that the points will be magnified on the map
#' @param stateCol color for state outlines on the map
#' @param stateLwd width for state outlines
#' @param countyCol color for county outline on the map
#' @param countyLwd width for county outlines
#' @param add logical specifying whether to add to the current plot
#' @param ... additional arguments passed to \code{maps::map()} such as
#'   \code{'projection'} or \code{'parameters'}
#'
#' @description
#' Creates a map of monitoring stations in a given ws_monitor object. Individual
#' monitor timeseries are reduced to a single value by applying the function
#' passed in as \code{slice} to the entire timeseries of each monitor with
#' \code{na.rm=TRUE}. These values are then plotted over a map of the United
#' States. Any additional arguments specified in '...' are passed on to the
#' \code{points()} function.
#'
#' If \code{slice} is an integer, it will be used as an index to pull out a
#' single timestep.
#'
#' If \code{slice} is a function (not a function name) it will be used with
#' argument \code{na.rm=TRUE} to collapse the time dimension. Thus, any user
#' defined functions passed in as \code{slice} must accept \code{na.rm} as a
#' parameter.
#'
#' @details
#' Using a single number for the \code{breaks} argument will result in the use
#' of quantiles to determine a set of breaks appropriate for the number of
#' colors.
#'
#' @examples
#' library(PWFSLSmoke)
#'
#' N_M <- monitor_subset(Northwest_Megafires, tlim = c(20150821,20150828))
#' monitor_map(N_M, cex = 2)
#' addAQILegend()

monitor_map <- function(
  ws_monitor,
  slice = get("max"),
  breaks = AQI$breaks_24,
  colors = AQI$colors,
  pch = par("pch"),
  cex = par("cex"),
  stateCol = "grey60",
  stateLwd = 2,
  countyCol = "grey70",
  countyLwd = 1,
  add = FALSE,
  ...
) {

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

  lon <- ws_monitor$meta$longitude
  lat <- ws_monitor$meta$latitude

  # Create the 'slice'
  # NOTE:  Need as.matrix in case we only have a single monitor
  allMissingMask <- apply(as.matrix(ws_monitor$data[, -1]), 2, function(x) { all(is.na(x)) } )
  data <- as.matrix(ws_monitor$data[, -1])
  if (class(slice) == "function") {
    pm25 <- apply(as.matrix(data[, !allMissingMask]), 2, slice, na.rm = TRUE)
  } else if (class(slice) == "integer" || class(slice) == "numeric") {
    pm25 <- data[as.integer(slice), ] # single row
  } else {
    stop("Improper use of slice parameter")
  }

  # Colors for each point
  cols <- aqiColors(pm25, palette = colors, bins = breaks)


  # ----- GRAPHICS -------------------------------------------------------------

  # Create the basemap
  if ( !add ) {

    stateCodes <- unique(ws_monitor$meta$stateCode)

    if ( is.null(stateCodes) || all(stateCodes == "") ) {

      # No stateCodes found. Use xlim and ylim.
      xlim <- range(ws_monitor$meta$longitude)
      ylim <- range(ws_monitor$meta$latitude)
      # add a 1 degree buffer
      xlim[1] <- xlim[1] - 1.0
      xlim[2] <- xlim[2] + 1.0
      ylim[1] <- ylim[1] - 1.0
      ylim[2] <- ylim[2] + 1.0
      # Plot the base map: state first, counties on top
      maps::map(
        "state",
        xlim = xlim, ylim = ylim,
        col = stateCol, lwd = stateLwd,
        ...
      )
      maps::map(
        "county",
        xlim = xlim, ylim = ylim,
        col = countyCol, lwd = countyLwd,
        add = TRUE, ...
      )

    } else {

      # Plot only the states containing the monitors
      # Need to get the maps package state names to be plotted in base map
      # We need to deal with things like "washington:whidbey island"
      stateCodes <- as.character(stateCodes)
      df <- maps::state.fips
      df$polyname <- stringr::str_replace(df$polyname, ":.*", "")
      df <- df %>% dplyr::filter(df$abb %in% stateCodes) %>% dplyr::distinct()
      stateNames <- df$polyname
      # Plot the base map: state first, counties on top
      maps::map("state", stateNames, col = stateCol, lwd = stateLwd, ...)
      maps::map("county", stateNames, col = countyCol, lwd = countyLwd, add = TRUE, ...)

    }

  }

  # Now we add the (potentially projected) monitor points

  # Set default graphical parameters unless they are passed in
  argsList <- list(...)

  if ( is.null(argsList$projection) ) {
    points(lon, lat, pch = pch, cex = cex, col = cols, xpd = NA)
  } else {
    points(mapproj::mapproject(lon, lat,
                               argsList$projection,
                               argsList$parameters,
                               argsList$orientation),
           pch = pch, cex = cex, col = cols, xpd = NA
    )
  }

}