add fun addAreaPolygons

DESCRIPTION

@@ -16,6 +16,7 @@ LazyData: true
 Imports: 
     geojsonsf,
     geosphere,
+    grDevices,
     htmltools,
     htmlwidgets,
     leaflet,

NAMESPACE

@@ -1,12 +1,14 @@
 # Generated by roxygen2: do not edit by hand
 
+export(addAreaPolygons)
 export(addCityShape)
 export(addProvinceShape)
 export(addTilesAmap)
 export(areaCalculator)
 export(convertCoordinates)
 import(sf)
 importFrom(Rcpp,sourceCpp)
+importFrom(grDevices,chull)
 importFrom(htmltools,tags)
 importFrom(htmlwidgets,prependContent)
 useDynLib(leafletZH, .registration = TRUE)

R/addAreaPolygons.R

@@ -0,0 +1,67 @@
+#' Add Area Polygons to a Map
+#'
+#' This function adds a polygon area to a given map using the specified latitude and longitude coordinates.
+#'
+#' @param map The map object to which the polygons will be added.
+#' @param longitude A vector of longitudes.
+#' @param latitude A vector of latitudes.
+#' @param coordinate A string indicating the coordinate system of the input data. Options are "WGS-84", "GCJ-02", "BD-09".
+#'
+#' @return The updated map object with added polygons.
+#' @export
+#'
+#' @examples
+#' library(leaflet)
+#' m <- leaflet() %>% addTilesAmap()
+#' m <- addAreaPolygons(m,
+#'   longitude = c(116.404, 116.407, 116.409),
+#'   latitude = c(39.916, 39.919, 39.917), coordinate = "WGS-84"
+#' )
+#' m
+addAreaPolygons <- function(map, longitude, latitude, coordinate = "WGS-84") {
+  # Check if latitude and longitude lengths match
+  if (length(latitude) != length(longitude)) {
+    stop("Latitude and longitude vectors must have the same length.")
+  }
+
+  # Validate the coordinate system
+  if (!coordinate %in% c("WGS-84", "GCJ-02", "BD-09")) {
+    stop("coordinate must be one of 'WGS-84', 'GCJ-02', and 'BD-09'")
+  }
+
+  # Create a data frame with the input coordinates
+  data <- data.frame(longitude = longitude, latitude = latitude)
+
+  # Convert coordinates to WGS-84 if necessary
+  if (coordinate == "GCJ-02") {
+    data <- purrr::map2_dfr(latitude, longitude, function(lat, lon) {
+      coords <- convertCoordinates(lat, lon, from = "GCJ-02", to = "WGS-84")
+      data.frame(longitude = coords[2], latitude = coords[1])
+    })
+  } else if (coordinate == "BD-09") {
+    data <- purrr::map2_dfr(latitude, longitude, function(lat, lon) {
+      coords <- convertCoordinates(lat, lon, from = "BD-09", to = "WGS-84")
+      data.frame(longitude = coords[2], latitude = coords[1])
+    })
+  }
+
+  # Remove duplicate points and create a convex hull to define the boundary
+  data <- data[!duplicated(data), ]
+  if (nrow(data) < 3) {
+    stop("At least three points are required to form a polygon.")
+  }
+
+  # Compute the convex hull and get the order of points
+  hull_index <- grDevices::chull(data$longitude, data$latitude)
+  hull_data <- data[hull_index, ]
+
+  # Add polygons to the map
+  map <- leaflet::addPolygons(map,
+    lng = hull_data$longitude,
+    lat = hull_data$latitude,
+    fillOpacity = 0.5,
+    color = "blue"
+  )
+
+  return(map)
+}

R/leafletZH-package.R

@@ -2,6 +2,7 @@
 "_PACKAGE"
 
 ## usethis namespace: start
+#' @importFrom grDevices chull
 #' @importFrom Rcpp sourceCpp
 #' @useDynLib leafletZH, .registration = TRUE
 ## usethis namespace: end