R: Test if points lie in convex hull

inhulln {geometry} | R Documentation

## Test if points lie in convex hull

### Description

Tests if a set of points lies within a convex hull, returning a boolean vector in which each element is `TRUE` if the corresponding point lies within the hull and `FALSE` if it lies outwith the hull or on one of its facets.

### Usage

    inhulln(ch, p)

### Arguments

`ch` | Convex hull produced using `convhulln`
`p` | An M-by-N matrix of points to test. The rows of `p` represent M points in N-dimensional space.

### Value

A boolean vector with M elements

### Author(s)

David Sterratt

### See Also

convhulln

### Examples

    p <- cbind(c(-1, -1, 1), c(-1, 1, -1))
    ch <- convhulln(p)
    ## First point should be in the hull; last two outside
    inhulln(ch, rbind(c(-0.5, -0.5),
                      c( 1  ,  1),
                      c(10  ,  0)))

    ## Test hypercube
    p <- rbox(4, B=1)
    ch <- convhulln(p)
    tp <-  cbind(seq(-1.9, 1.9, by=0.2), 0, 0, 0)
    pin <- inhulln(ch, tp)
    ## Points on x-axis should be in box only between -1 and 1
    pin == (tp[,1] < 1 & tp[,1] > -1)

[Package geometry version 0.4.0 Index]