voronoiPolygons {cholera}

Extract vertices of Delaunay triangles and Dirichelet (Voronoi) tiles.

Description

For construction and plotting of Delaunay and Voronoi polygons.

Usage

voronoiPolygons(sites, rw.data = NULL, rw = NULL, type = "tiles",
  output = "vertices", latlong = FALSE)

Arguments

sites

Object. Data frame of sites to compute Delaunay triangulation and Dirichelet (Voronoi) tessellation with variables "x" and "y".

rw.data

Object. Data frame of secondary source of data to set the rectangular window or bounding box: observations, cases, etc. with variables "x" and "y".

rw

Numeric. Alternative to rw.data: vector of corners to define the rectangular window or bounding box: xmin, xmax, ymin, ymax.

type

Character. "tiles" (tessellation) or "triangles" (triangulation) vertices.

output

Character. "vertices" or "polygons". "vertices" re "polygons" will draw base R polygons() to an existing plot.

latlong

Logical. Use estimated longitude and latitude.

Value

An R list of data frames or base R graphics polygon()'s'.

Note

This function relies on the 'deldir' package.

Examples

snowMap()
voronoiPolygons(pumps, output = "polygons")

snowMap()
voronoiPolygons(pumps, roads, output = "polygons")

snowMap()
voronoiPolygons(pumps, roads, type = "triangles", output = "polygons")

vertices <- voronoiPolygons(pumps, roads)
snow.colors <- grDevices::adjustcolor(snowColors(), alpha.f = 1/3)
snowMap(add.cases = FALSE)
invisible(lapply(seq_along(vertices), function(i) {
  polygon(vertices[[i]], col = snow.colors[[i]])
}))