voronoiPolygons {cholera}R Documentation

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

Description

For construction and plotting of Delauny and Voronoi polygons.

Usage

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

Arguments

sites

Object. Data frame of sites to compute Delauny 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.

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]])
}))

[Package cholera version 0.7.5 Index]