Create a list of Delaunay triangles
From an object of class “deldir” produces a list of the Delaunay triangles in the triangulation of a set of points in the plane.
triang.list(object)
object |
An object of class “deldir” as produced by |
A list each of whose components is a 3 x 3, 3 x 4 or 3 x 5 data frame corresponding to one of the Delaunay triangles specified by “object”. The rows of each such data frame correspond to the vertices of the corresponding Delaunay triangle. The columns are:
ptNum (the index of the point in the original sequence
of points that is being triangulated. Note that if a point is
one of a set of duplicated points then ptNum is
the first of the indices of the points in this set.)
ptType (the type of the vertex; “data”
or “dummy”; present only if there were any dummy points
specified)
x (the x-coordinate of the vertex)
y (the x-coordinate of the vertex)
z (the “auxiliary value” or “weight”
z associated with the vertex; present only if such values
were supplied in the call to deldir())
The returned value has an attribute “rw” consisting of the enclosing rectangle of the triangulation.
The code of this function was taken more-or-less directly from code written by Adrian Baddeley for the “delaunay()” function in the “spatstat” package.
Rolf Turner r.turner@auckland.ac.nz
deldir(), plot.triang.list(),
tile.list(), plot.tile.list()
set.seed(42) x <- runif(20) y <- runif(20) z <- sample(1:100,20) d <- deldir(x,y,z=z) ttt <- triang.list(d)
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