R: Search for the enclosing Delaunay convex hull

tsearch {geometry} | R Documentation

## Search for the enclosing Delaunay convex hull

### Description

For `t <- delaunay(cbind(x, y))`, where `(x, y)` is a 2D set of points, `tsearch(x, y, t, xi, yi)` finds the index in `t` containing the points `(xi, yi)`. For points outside the convex hull the index is `NA`.

### Usage

    tsearch(x, y, t, xi, yi, bary = FALSE, method = "quadtree")

### Arguments

`x` | X-coordinates of triangulation points
`y` | Y-coordinates of triangulation points
`t` | Triangulation, e.g. produced by `t <- delaunayn(cbind(x, y))`
`xi` | X-coordinates of points to test
`yi` | Y-coordinates of points to test
`bary` | If `TRUE` return barycentric coordinates as well as index of triangle.
`method` | One of `"quadtree"` or `"orig"`. The Quadtree algorithm is much faster and new from version 0.4.0. The `orig` option uses the tsearch algorithm adapted from Octave code. Its use is deprecated and it may be removed from a future version of the package.

### Value

If `bary` is `FALSE`, the index in `t` containing the points `(xi, yi)`. For points outside the convex hull the index is `NA`. If `bary` is `TRUE`, a list containing:

list("idx")

  the index in `t` containing the points `(xi, yi)`

list("p")

  a 3-column matrix containing the barycentric coordinates with respect to the enclosing triangle of each point `(xi, yi)`.

### Note

The original Octave function is Copyright (C) 2007-2012 David Bateman

### Author(s)

Jean-Romain Roussel (Quadtree algorithm), David Sterratt (Octave-based implementation)

### See Also

`tsearchn`, `delaunayn`

[Package geometry version 0.4.2 Index]