alphahull (version 2.2)

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

Description

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

Usage

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.

Value

in.ahull

A logical vector specifying whether each point in \(p\) belongs to the \(\alpha\)-convex hull.

Details

The complement of the \(\alpha\)-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.

See Also

ahull, complement.

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)
# 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)))
# }

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