# inahull: Determines for one or more points whether they belong to the... In alphahull: Generalization of the Convex Hull of a Sample of Points in the Plane

## Description

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

## Usage

 `1` ```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

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13``` ```## 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) ```

### Example output

``` TRUE
  TRUE FALSE
```

alphahull documentation built on June 22, 2019, 1:02 a.m.