R/polar_percentileMap.R

In davidcarslaw/openairmaps: Create Maps of Air Pollution Data

#' Percentile roses on dynamic and static maps
#'
#' The [percentileMap()] function creates a map using polar percentile roses as
#' markers. Any number of pollutants can be specified using the `pollutant`
#' argument, and multiple layers of markers can be created using `type`. By
#' default, these maps are dynamic and can be panned, zoomed, and otherwise
#' interacted with. Using the `static` argument allows for static images to be
#' produced instead.
#'
#' @inheritSection polarMap Customisation of static maps using ggplot2
#' @family directional analysis maps
#'
#' @inheritParams polarMap
#' @param percentile *The percentile values for the colour scale bin.*
#'
#'  *default:* `c(25, 50, 75, 90, 95)` | *scope:* dynamic & static
#'
#'   The percentile value(s) to plot using [openair::percentileRose()]. Must be
#'   a vector of values between `0` and `100`. If `percentile = NA` then only a
#'   mean line will be shown.
#'
#' @param intervals *Specifier for the percentile rose radial axis intervals.*
#'
#'  *default:* `"fixed"` | *scope:* dynamic & static
#'
#'   One of:
#' - `"fixed"` (the default) which ensures all of the markers use the same radial axis scale.
#' - `"free"` which allows all of the markers to use different radial axis scales.
#' - A numeric vector defining a sequence of numbers to use as the intervals, e.g., `intervals = c(0, 10, 30, 50)`.
#'
#' @inheritDotParams openair::percentileRose -mydata -pollutant -percentile
#'   -type -cols -key -plot -intervals
#' @returns Either:
#'
#'  - *Dynamic:* A leaflet object
#'  - *Static:* A `ggplot2` object using [ggplot2::coord_sf()] coordinates with a `ggspatial` basemap
#' @export
#'
#' @seealso [openair::percentileRose()]
#'
#' @examples
#' \dontrun{
#' percentileMap(polar_data,
#'   pollutant = "nox",
#'   provider = "CartoDB.Voyager"
#' )
#' }
percentileMap <- function(data,
                          pollutant = NULL,
                          percentile = c(25, 50, 75, 90, 95),
                          intervals = "fixed",
                          latitude = NULL,
                          longitude = NULL,
                          crs = 4326,
                          type = NULL,
                          popup = NULL,
                          label = NULL,
                          provider = "OpenStreetMap",
                          cols = "turbo",
                          alpha = 1,
                          key = FALSE,
                          legend = TRUE,
                          legend.position = NULL,
                          legend.title = NULL,
                          legend.title.autotext = TRUE,
                          control.collapsed = FALSE,
                          control.position = "topright",
                          control.autotext = TRUE,
                          d.icon = 200,
                          d.fig = 3.5,
                          static = FALSE,
                          static.nrow = NULL,
                          ...) {
  # check basemap providers are valid
  provider <- check_providers(provider, static)
  legend.position <- check_legendposition(legend.position, static)

  # check for old facet/control opts
  type <- type %||% check_facet_control(...)

  # assume lat/lon
  latlon <- assume_latlon(
    data = data,
    latitude = latitude,
    longitude = longitude
  )
  latitude <- latlon$latitude
  longitude <- latlon$longitude

  # auto limits
  intervals <- check_multipoll(intervals, pollutant)

  if ("fixed" %in% intervals) {
    data <-
      dplyr::mutate(data, latlng = paste(.data[[latitude]], .data[[longitude]]))

    fixed_type <- type
    if (is.null(type)) {
      fixed_type <- "default"
    }

    testplots <-
      openair::percentileRose(
        data,
        pollutant = pollutant,
        type = c("latlng", fixed_type),
        plot = FALSE
      )$data

    theIntervals <- pretty(testplots[[pollutant]])
  } else if ("free" %in% intervals) {
    theIntervals <- NULL
  } else if (is.numeric(intervals)) {
    theIntervals <- intervals
  } else {
    cli::cli_abort(
      c(
        "!" = "Do not recognise {.field intervals} value of {.code {intervals}}",
        "i" = "{.field intervals} should be one of {.code 'fixed'}, {.code 'free'} or a numeric vector."
      )
    )
  }

  # cut data
  data <- quick_cutdata(data = data, type = type)

  # deal with popups
  if (length(popup) > 1) {
    data <-
      quick_popup(
        data = data,
        popup = popup,
        latitude = latitude,
        longitude = longitude,
        control = type
      )
    popup <- "popup"
  }

  # prep data
  data <-
    prepMapData(
      data = data,
      pollutant = pollutant,
      control = type,
      "wd",
      latitude,
      longitude,
      popup,
      label
    )

  # identify splitting column (defaulting to pollutant)
  if (length(pollutant) > 1) {
    split_col <- "pollutant_name"
  } else if (!is.null(type)) {
    data[type] <- as.factor(data[[type]])
    split_col <- type
  } else {
    split_col <- "pollutant_name"
  }

  # define function
  fun <- function(data) {
    openair::percentileRose(
      data,
      pollutant = "conc",
      percentile = percentile,
      plot = FALSE,
      cols = cols,
      alpha = alpha,
      key = key,
      intervals = theIntervals,
      ...,
      par.settings = list(axis.line = list(col = "transparent"))
    )$plot
  }

  # plot and save static markers
  plots_df <-
    create_polar_markers(
      fun = fun,
      data = data,
      latitude = latitude,
      longitude = longitude,
      split_col = split_col,
      d.fig = d.fig,
      popup = popup,
      label = label
    )

  if (static) {
    # create static map - deals with basics & facets
    map <-
      create_static_map(
        plots_df = plots_df,
        latitude = latitude,
        longitude = longitude,
        split_col = split_col,
        pollutant = pollutant,
        facet = type,
        facet.nrow = static.nrow,
        d.icon = d.icon,
        crs = crs,
        provider = provider
      )

    # create legend
    percs <- unique(c(0, percentile))
    intervals <-
      stringr::str_c(percs, dplyr::lead(percs), sep = " - ")
    intervals <- intervals[!is.na(intervals)]
    intervals <- factor(intervals, intervals)
    pal <-
      openair::openColours(scheme = cols, n = length(intervals)) %>%
      stats::setNames(intervals)

    # create dummy df for creating legend
    dummy <-
      dplyr::distinct(plots_df, .data[[longitude]], .data[[latitude]]) %>%
      tidyr::crossing(intervals)

    if (legend) {
      legend.title <-
        create_legend_title(
          static = static,
          legend.title.autotext = legend.title.autotext,
          legend.title = legend.title,
          str = "Percentile"
        )

      map <-
        map +
        ggplot2::geom_point(
          data = dummy,
          ggplot2::aes(.data[[longitude]], .data[[latitude]],
            fill = .data[["intervals"]]
          ),
          size = 0,
          key_glyph = ggplot2::draw_key_rect
        ) +
        ggplot2::scale_fill_manual(values = pal, drop = FALSE) +
        ggplot2::labs(fill = legend.title) +
        ggplot2::theme(legend.position = legend.position)
    }
  }

  if (!static) {
    # create leaflet map
    map <-
      make_leaflet_map(
        plots_df,
        latitude,
        longitude,
        crs,
        provider,
        d.icon,
        popup,
        label,
        split_col,
        control.collapsed,
        control.position,
        control.autotext
      )

    legend.title <-
      create_legend_title(
        static = static,
        legend.title.autotext = legend.title.autotext,
        legend.title = legend.title,
        str = "Percentile"
      )

    # add legend
    if (all(!is.na(percentile)) & legend) {
      percs <- unique(c(0, percentile))
      map <-
        leaflet::addLegend(
          map,
          title = legend.title,
          position = legend.position,
          pal = leaflet::colorBin(
            palette = openair::openColours(scheme = cols, n = length(percs)),
            bins = percs,
            domain = 0:100
          ),
          values = 0:100
        )
    }
  }

  # return map
  return(map)
}