Determines for one or more points whether they belong to the alpha-convex hull

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Description

This function determines for one or more points p whether they belong to the α-convex hull of a sample.

Usage

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inahull(ahull.obj, p)

Arguments

ahull.obj

Object of class "ahull" returned by the funcion ahull.

p

Numeric vector with two components describing a point in the plane or two-column matrix of points.

Details

The complement of the α-convex hull of a sample is calculated by complement. The function inahull checks whether each point in p belongs to any of the open balls or halfplanes that define the complement.

Value

in.ahull

A logical vector specifying whether each point in p belongs to the α-convex hull.

See Also

ahull, complement.

Examples

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## 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)
# Check if the point (0.5, 0.5) belongs to the alpha-convex hull
inahull(ahull.obj, p = c(0.5, 0.5))
# Check if the points (0.5, 0.5) and (2, 2) belong to the alpha-convex hull
inahull(ahull.obj, p = rbind(c(0.5, 0.5), c(2, 2)))

## End(Not run)