R: Determines for one or more points whether they belong to the...

inahull {alphahull} | R Documentation

## 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 α-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.

### 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

    ## 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)

[Package alphahull version 2.2 Index]