R/geos-polygonize.R

In geos: Open Source Geometry Engine ('GEOS') R API

#' Create polygons from noded edges
#'
#' @param collection A GEOMETRYCOLLECTION or MULTILINESTRING of
#'   edges that meet at their endpoints.
#'
#' @return A GEOMETRYCOLLECTION of polygons
#' @export
#'
#' @examples
#' geos_polygonize("MULTILINESTRING ((0 0, 0 1), (0 1, 1 0), (1 0, 0 0))")
#' geos_polygonize_valid("MULTILINESTRING ((0 0, 0 1), (0 1, 1 0), (1 0, 0 0))")
#' geos_polygonize_cut_edges("MULTILINESTRING ((0 0, 0 1), (0 1, 1 0), (1 0, 0 0))")
#'
geos_polygonize <- function(collection) {
  collection <- sanitize_geos_geometry(collection)
  stopifnot(length(collection) == 1)

  new_geos_geometry(
    list(.Call(geos_c_polygonize, unclass(collection)[[1]])),
    crs = attr(collection, "crs", exact = TRUE)
  )
}

#' @rdname geos_polygonize
#' @export
geos_polygonize_valid <- function(collection) {
  collection <- sanitize_geos_geometry(collection)
  stopifnot(length(collection) == 1)

  new_geos_geometry(
    list(.Call(geos_c_polygonize_valid, unclass(collection)[[1]])),
    crs = attr(collection, "crs", exact = TRUE)
  )
}

#' @rdname geos_polygonize
#' @export
geos_polygonize_cut_edges <- function(collection) {
  collection <- sanitize_geos_geometry(collection)
  stopifnot(length(collection) == 1)

  new_geos_geometry(
    list(.Call(geos_c_polygonize_cut_edges, unclass(collection)[[1]])),
    crs = attr(collection, "crs", exact = TRUE)
  )
}

#' @rdname geos_polygonize
#' @export
geos_polygonize_full <- function(collection) {
  collection <- sanitize_geos_geometry(collection)
  stopifnot(length(collection) == 1)

  result <- new_geos_geometry(
    .Call(geos_c_polygonize_full, unclass(collection)[[1]]),
    crs = attr(collection, "crs", exact = TRUE)
  )

  list(
    result = result[1],
    cut_edges = result[2],
    dangles = result[3],
    invalid_rings = result[4]
  )
}