geometry: tsearch – R documentation

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tsearch

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

Author(s)

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