R: Plot the alpha-convex hull

plot.ahull {alphahull} | R Documentation

## 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)

[Package alphahull version 2.2 Index]