Nothing
#' Convert polygons to topological boundaries (lines)
#'
#' @param input input polygons object to convert to inner lines. One of:
#' \itemize{
#' \item \code{geo_json} or \code{character} polygons;
#' \item \code{SpatialPolygons*};
#' \item \code{sf} or \code{sfc} polygons object
#' }
#' @param fields character vector of field names. If left as \code{NULL}
#' (default), external (unshared) boundaries are attributed as TYPE 0 and
#' internal (shared) boundaries are TYPE 1. Giving a field name adds an
#' intermediate level of hierarchy at TYPE 1, with the lowest-level internal
#' boundaries set to TYPE 2. Supplying a character vector of field names adds
#' additional levels of hierarchy.
#' @inheritDotParams apply_mapshaper_commands force_FC sys sys_mem quiet
#'
#' @return topological boundaries as lines, in the same class as the input
#'
#' @examples
#'
#' library(geojsonsf)
#' library(sf)
#'
#' poly <- structure('{"type":"FeatureCollection",
#' "features":[
#' {"type":"Feature",
#' "properties":{"foo": "a"},
#' "geometry":{"type":"Polygon","coordinates":[[
#' [102,2],[102,3],[103,3],[103,2],[102,2]
#' ]]}}
#' ,{"type":"Feature",
#' "properties":{"foo": "a"},
#' "geometry":{"type":"Polygon","coordinates":[[
#' [103,3],[104,3],[104,2],[103,2],[103,3]
#' ]]}},
#' {"type":"Feature",
#' "properties":{"foo": "b"},
#' "geometry":{"type":"Polygon","coordinates":[[
#' [102.5,1],[102.5,2],[103.5,2],[103.5,1],[102.5,1]
#' ]]}}]}', class = c("geojson", "json"))
#'
#' poly <- geojson_sf(poly)
#' summary(poly)
#' plot(poly)
#'
#' out <- ms_lines(poly)
#' summary(out)
#' plot(out)
#'
#' @export
ms_lines <- function(input, fields = NULL, ...) {
if (!is.null(fields) && !is.character(fields)) stop("fields must be a character vector of field names")
UseMethod("ms_lines")
}
#' @export
ms_lines.character <- function(input, fields = NULL, ...) {
input <- check_character_input(input)
command <- make_lines_call(fields)
apply_mapshaper_commands(data = input, command = command, ...)
}
#' @export
ms_lines.json <- function(input, fields = NULL, ...) {
command <- make_lines_call(fields)
apply_mapshaper_commands(data = input, command = command, ...)
}
#' @export
ms_lines.SpatialPolygons <- function(input, fields = NULL, ...) {
if (.hasSlot(input, "data")) {
if (!all(fields %in% names(input@data))) {
stop("not all fields specified exist in input data")
}
}
command <- make_lines_call(fields)
ms_sp(input, command, ...)
}
#' @export
ms_lines.sf <- function(input, fields = NULL, ...) {
if (!all(fields %in% names(input))) {
stop("not all fields specified exist in input data")
}
lines_sf(input = input, fields = fields, ...)
}
#' @export
ms_lines.sfc <- function(input, fields = NULL, ...) {
if (!is.null(fields)) {
stop("Do not specify fields for sfc classes", call. = FALSE)
}
lines_sf(input = input, fields = fields, ...)
}
lines_sf <- function(input, fields, ...) {
if (!all(sf::st_is(input, c("POLYGON", "MULTIPOLYGON")))) {
stop("ms_lines only works with (MULTI)POLYGON")
}
command <- make_lines_call(fields)
ms_sf(input, command, ...)
}
make_lines_call <- function(fields) {
if(!is.null(fields) && !is.character(fields)) stop("fields must be a character vector of field names")
fields <- paste0(fields, collapse = ",")
call <- list("-lines", fields)
call
}
Any scripts or data that you put into this service are public.
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.