R/mapping.R

In kstierhoff/atm: Functions Used for the Analysis of Acoustic-Trawl Method (ATM) Survey Data

#' Create basemap
#'
#' @param nav Data frame containing navigation data, used to set map boundaries.
#' @param states Simple feature with state boundaries.
#' @param countries Simple feature with country boundaries.
#' @param labels A data frame with names and locations of landmark labels.
#' @param bathy Simple feature with bathymetr contours.
#' @param boundaries User-specified bounding box (optional).
#' @param crs Coordinate reference system (CRS) for map projection.
#' @param add.labels Add landmark labels (TRUE/FALSE).
#' @return A ggplot2 map object.
#' @importFrom magrittr "%>%"
#' @examples
#' get_basemap(nav, states, countries, landmarks, bathy, crs = 3310)
#' @export
get_basemap <- function(nav, states, countries, labels, bathy, boundaries = NULL,
                        add.labels = TRUE, crs) {
  if (is.null(boundaries)) {
    # Define boundaries using nav input
    map.bounds <- nav %>%
      sf::st_transform(crs = crs) %>%
      sf::st_bbox()
  } else {
    # Use user-provided bbox
    map.bounds <- boundaries
  }

  if (add.labels) {
    # Create map object
    ggplot2::ggplot() +
      # Plot bathymetry contours
      ggplot2::geom_sf(data = bathy, colour = "gray90", alpha = 0.5) +
      # # Plot high-res land polygons
      ggplot2::geom_sf(data = countries, fill = "gray90", colour = "gray50") +
      ggplot2::geom_sf(data = states, fill = "gray90", colour = "gray50") +
      # Plot landmarks
      ggplot2::geom_point(data = labels, ggplot2::aes(X, Y), size = 2, colour = 'gray50') +
      shadowtext::geom_shadowtext(data  = labels, ggplot2::aes(X, Y, label = name),
                                  colour = 'gray20', size = 2, fontface = 'bold',
                                  hjust = 0, nudge_x = 0.2, nudge_y = 0.05, angle = 25,
                                  bg.colour = "white") +
      # Format axes and titles
      ggplot2::xlab("Longitude") + ggplot2::ylab("Latitude") +
      ggplot2::coord_sf(crs = crs,
                        xlim = c(map.bounds["xmin"], map.bounds["xmax"]),
                        ylim = c(map.bounds["ymin"], map.bounds["ymax"])) +
      theme_bw() +
      theme(axis.text.y          = element_text(angle = 90, hjust = 0.5),
            legend.position      = c(0,0),
            legend.justification = c(0,0),
            legend.background    = element_blank(),
            legend.key           = element_blank(),
            plot.title           = element_text(hjust = 0.5),
            panel.grid.major     = element_line(color = "gray90")) +
      # Add scale bar
      ggspatial::annotation_scale(style = "ticks", location = "br", height = unit(0.15, "cm"))
  } else {
    # Create map object
    ggplot2::ggplot() +
      # Plot bathymetry contours
      ggplot2::geom_sf(data = bathy, colour = "gray90", alpha = 0.5) +
      # Plot high-res land polygons
      ggplot2::geom_sf(data = countries, fill = "gray90", colour = "gray50") +
      ggplot2::geom_sf(data = states, fill = "gray90", colour = "gray50") +
      # Format axes and titles
      ggplot2::xlab("Longitude") + ggplot2::ylab("Latitude") +
      ggplot2::coord_sf(crs = crs,
                        xlim = c(map.bounds["xmin"], map.bounds["xmax"]),
                        ylim = c(map.bounds["ymin"], map.bounds["ymax"])) +
      theme_bw() +
      theme(axis.text.y          = element_text(angle = 90, hjust = 0.5),
            legend.position      = c(0,0),
            legend.justification = c(0,0),
            legend.background    = element_blank(),
            legend.key           = element_blank(),
            plot.title           = element_text(hjust = 0.5),
            panel.grid.major     = element_line(color = "gray90")) +
      # Add scale bar
      ggspatial::annotation_scale(style = "ticks", location = "br", height = unit(0.15, "cm"))
  }
}