Description Usage Arguments Value Acknowledgement Warning Author(s) See Also Examples
For each point in the set being tessellated produces a list entry describing the Dirichlet/Voronoi tile containing that point.
1 
object 
An object of class 
minEdgeLength 
Positive numeric scalar specifying the minimum length that
an edge of a tile may have. It is used to eliminate edges
that are effectively of zero length, which can cause tiles
to be “invalid”. This argument defaults to

clipp 
An object specifying a polygon to which the tessellation, whose tiles are being determined, should be clipped. It should consist either of:
If this argument is provided then the tiles in the list that
is produced are “clipped” to the polygon specified by

A list with one entry for each of the points in the set being
tesselated, or for each of the tiles that are retained after clipping
if clipp
is not NULL
. Each entry is in turn a list
with a number of components. These components always include:
ptNum 
The index of the point in the original sequence of points
that is being tessellated. Note that if a point is one of a set
of duplicated points then 
pt 
The coordinates of the point whose tile is being described. 
area 
The area of the tile. 
If the tile in question has not been subdivided by the clipping process then the list components also include:
x 
The 
y 
The 
bp 
Vector 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. 
If the tile in question has been subdivided then the list
does not have the foregoing three components but rather has a
component tileParts
which is in turn a list of length equal
to the number of parts into which the tile was subdivided. Each
component of tileParts
is yet another list with four
components x
, y
, bp
and area
as described above
and as are appropriate for the part in question.
The components of the overall list for each tile may also include:
ptType 
The “type” of the 
z 
The “auxiliary value” or “weight” associated
with the 
The author expresses sincere thanks to Majid Yazdani who found and
pointed out a serious bug in tile.list
in a previous version
(0.05) of the deldir
package.
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 included 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.
Rolf Turner r.turner@auckland.ac.nz
deldir()
, plot.tile.list()
triang.list()
plot.triang.list()
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20  set.seed(42)
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)
if(require(polyclip)) {
CP < list(x=c(0.49,0.35,0.15,0.20,0.35,0.42,
0.43,0.62,0.46,0.63,0.82,0.79),
y=c(0.78,0.86,0.79,0.54,0.58,0.70,
0.51,0.46,0.31,0.20,0.37,0.54))
wc < tile.list(z,clipp=CP) # 10 tiles are retained; the third tile,
# corresponding to point 6, is
# subdivided into two parts.
}

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