plot.ahull: Plot the alpha-convex hull

In alphahull: Generalization of the Convex Hull of a Sample of Points in the Plane

Plot the alpha-convex hull

Description

This function returns a plot of the α-convex hull. If desired, it also adds the Delaunay triangulation, Voronoi diagram and α-shape of the sample.

Usage

## S3 method for class 'ahull'
plot(x, add = FALSE, do.shape = FALSE, 
	wlines = c("none", "both", "del", "vor"), wpoints = TRUE, 
	number = FALSE, col = NULL, xlim = NULL, 
	ylim = NULL, lwd = NULL, ...)

Arguments

x	Object of class "ahull".
add	Logical, if TRUE add to a current plot.
do.shape	Logical, indicates if the α-shape should also be plotted.
wlines	"Which lines?". I.e. should the Delaunay triangulation be plotted (wlines='del'), should the Voronoi diagram be plotted (wlines='vor'), should both be plotted (wlines='both'), or none (wlines='none', the default)?
wpoints	Logical, indicates if sample points should be plotted.
number	Logical, defaulting to FALSE; if TRUE then the points plotted will be labelled with their index numbers.
col	The colour numbers for plotting the α-convex hull, α-shape, data points, Delaunay triangulation, Voronoi diagram, and the point numbers, in that order; defaults to c(1,1,1,1,1,1). If fewer than six numbers are given, they are recycled. (If more than six numbers are given, the redundant ones are ignored.)
xlim	The limits on the x-axis.
ylim	The limits on the y-axis.
lwd	The line widths for plotting the tesselations, the α-shape, and the α-convex hull, in that order; defaults to c(1,1,2).
...	Arguments to be passed to methods, such as graphical parameters (see par).

See Also

ahull, ashape.

Examples

## Not run: 
# Random sample in the unit square
x <- matrix(runif(100), nc = 2)
# Value of alpha
alpha <- 0.2
# alpha-convex hull
ahull.obj <- ahull(x, alpha = alpha)
# Plot including the alpha-convex hull in pink, alpha-shape in blue, 
# sample points in black, voronoi diagram in green 
# and Delaunay triangulation in red 
plot(ahull.obj, do.shape = TRUE, wlines = "both", col = c(6, 4, 1, 2, 3))

# Random sample  from a uniform distribution on a Koch snowflake 
# with initial side length 1 and 3 iterations
x <- rkoch(2000, side = 1, niter = 3)
# Value of alpha
alpha <- 0.05
# Alpha-convex hull
ahull.obj <- ahull(x, alpha = alpha)
plot(ahull.obj)

## End(Not run)

alphahull documentation built on June 16, 2022, 5:10 p.m.