mdsumner/shared-mapedit.R

## shared-mapedit.R
#' NOTE: improved work-in-progress here MDSumner 2017-08-02
#' https://github.com/mdsumner/gibble/blob/master/inst/examples/gibble_rebuild.R


#' function to illustrate topological editing of simple features
#'
#' Note that this uses the sc and scsf packages which have a much
#' grander goal than de-duplicating vertices and re-composing simple
#' features. The logic used can be trivially isolated into a small set
#' of functions for use in mapedit, or perhaps a separate package.
#'
#' Limited to pure edit of the points with no live redraw.
#' @param x simple features object, supported by scsf/sc::PATH
#' @param map mapview object
topoedit.sf <- function(x, map = NULL) {
  ##devtools::install_github("mdsumner/sc")
  ##devtools::install_github("mdsumner/scsf")
  require(scsf)
  require(sc)
  ## build the topological version
  ## all we really get are shared vertices for now
  prim <- sc::PATH(x)

  ## create point-versions we can identify
  sf_points <- sf::st_as_sf(prim$vertex, coords = c("x_", "y_"), crs = st_crs(x))
  if (is.null(map)) map <- mapview::mapview()
  map <- map + mapview::mapview(x) + mapview(sf_points)
  edited <- editFeatures(sf_points, map = map)
  prim$vertex <- edited %>% dplyr::select(vertex_) %>% dplyr::bind_cols(sc_coord(edited))
  scsf::sf(prim)
}

#mapview() + mapview(minimal_mesh)
a <- topoedit.sf(minimal_mesh)


## a more involved example
north_carolina <- read_sf(system.file("shape/nc.shp", package="sf"))
## pick one and its neighbours
library(dplyr)
set.seed(1)
path <- sc::PATH(north_carolina)
sample_feature <- path$object %>% sample_n(1) %>% select(object_, FIPS)
## this is very convoluted, just used to pick the neighbours (by vertex)
## of our one selected feature, but also shows the simple relation
## between the PATH tables that link a single de-duplicated vertex pool
neighbours <- sample_feature %>%
  inner_join(path$path) %>% inner_join(path$path_link_vertex) %>%
  distinct(vertex_) %>% inner_join(path$path_link_vertex) %>%
  distinct(path_) %>% inner_join(path$path)  %>%
  distinct(object_) %>% inner_join(path$object) %>%
  select(FIPS) %>% inner_join(north_carolina) %>% sf::st_as_sf()
neighbours$sample <- neighbours$FIPS == sample_feature$FIPS
plot(neighbours[c("sample")])
plot(north_carolina, add = TRUE, colour = NA)


## here we only can edit points, and that's all we can see happening
## but the result is used to rebuild the features with those updates
## to the de-duplicated vertex pool
b <- topoedit.sf(neighbours)
plot(b["sample"])
plot(neighbours, add = TRUE, col = NA, lwd = 4)
	#' NOTE: improved work-in-progress here MDSumner 2017-08-02
	#' https://github.com/mdsumner/gibble/blob/master/inst/examples/gibble_rebuild.R


	#' function to illustrate topological editing of simple features
	#'
	#' Note that this uses the sc and scsf packages which have a much
	#' grander goal than de-duplicating vertices and re-composing simple
	#' features. The logic used can be trivially isolated into a small set
	#' of functions for use in mapedit, or perhaps a separate package.
	#'
	#' Limited to pure edit of the points with no live redraw.
	#' @param x simple features object, supported by scsf/sc::PATH
	#' @param map mapview object
	topoedit.sf <- function(x, map = NULL) {
	##devtools::install_github("mdsumner/sc")
	##devtools::install_github("mdsumner/scsf")
	require(scsf)
	require(sc)
	## build the topological version
	## all we really get are shared vertices for now
	prim <- sc::PATH(x)

	## create point-versions we can identify
	sf_points <- sf::st_as_sf(prim$vertex, coords = c("x_", "y_"), crs = st_crs(x))
	if (is.null(map)) map <- mapview::mapview()
	map <- map + mapview::mapview(x) + mapview(sf_points)
	edited <- editFeatures(sf_points, map = map)
	prim$vertex <- edited %>% dplyr::select(vertex_) %>% dplyr::bind_cols(sc_coord(edited))
	scsf::sf(prim)
	}

	#mapview() + mapview(minimal_mesh)
	a <- topoedit.sf(minimal_mesh)


	## a more involved example
	north_carolina <- read_sf(system.file("shape/nc.shp", package="sf"))
	## pick one and its neighbours
	library(dplyr)
	set.seed(1)
	path <- sc::PATH(north_carolina)
	sample_feature <- path$object %>% sample_n(1) %>% select(object_, FIPS)
	## this is very convoluted, just used to pick the neighbours (by vertex)
	## of our one selected feature, but also shows the simple relation
	## between the PATH tables that link a single de-duplicated vertex pool
	neighbours <- sample_feature %>%
	inner_join(path$path) %>% inner_join(path$path_link_vertex) %>%
	distinct(vertex_) %>% inner_join(path$path_link_vertex) %>%
	distinct(path_) %>% inner_join(path$path) %>%
	distinct(object_) %>% inner_join(path$object) %>%
	select(FIPS) %>% inner_join(north_carolina) %>% sf::st_as_sf()
	neighbours$sample <- neighbours$FIPS == sample_feature$FIPS
	plot(neighbours[c("sample")])
	plot(north_carolina, add = TRUE, colour = NA)


	## here we only can edit points, and that's all we can see happening
	## but the result is used to rebuild the features with those updates
	## to the de-duplicated vertex pool
	b <- topoedit.sf(neighbours)
	plot(b["sample"])
	plot(neighbours, add = TRUE, col = NA, lwd = 4)