tile.list: Create a list of tiles in a tessellation
Description
For each point in the set being tessellated produces a list
entry describing the Dirichlet/Voronoi tile containing that
point.
Usage
tile.list(object)
Arguments
object
An object of class deldir as produced
by the function deldir().
Value
A list with one entry for each of the points in the set
being tesselated. Each entry is in turn a list with
components
ptThe coordinates of the point whose tile is being described.
xThe x coordinates of the vertices of the tile, in
anticlockwise order.
yThe y coordinates of the vertices of the tile, in
anticlockwise order.
bpVector of logicals indicating whether the tile vertex is a
``real'' vertex, or a boundary point, i.e. a point where the
tile edge intersects the boundary of the enclosing rectangle
Acknowledgement
The author expresses sincere thanks to Majid Yazdani who found and
pointed out a serious bug in tile.list in a previous version
(0.0-5) of the deldir package.
Warning
The set of vertices of each tile may be ``incomplete''. Only
vertices which lie within the enclosing rectangle, and ``boundary
points'' are listed.
Note that the enclosing rectangle may be specified by the user
in the call to deldir().
In contrast to some earlier versions of deldir, the corners
of the enclosing rectangle are now include as vertices of tiles.
I.e. a tile which in fact extends beyond the rectangular window
and contains a corner of that window will have that corner added
to its list of vertices. Thus the corresponding polygon is the
intersection of the tile with the enclosing rectangle.
x <- runif(20)
y <- runif(20)
z <- deldir(x,y)
w <- tile.list(z)
z <- deldir(x,y,rw=c(0,1,0,1))
w <- tile.list(z)
z <- deldir(x,y,rw=c(0,1,0,1),dpl=list(ndx=2,ndy=2))
w <- tile.list(z)