Generics/Methods for polygon objects
Some generic functions and methods for polygon objects
append.poly(x, y) area.poly(object, ...) get.pts(object) get.bbox(x) scale.poly(x, ...) tristrip(x) triangulate(x)
x,object |
A polygon object |
y |
A polygon object |
... |
Other arguments passed to methods |
The result of tristrip(x) is a list of two-column matrices. Each
matrix is a tristrip, i.e. the rows are vertices of triangles, with
each overlapping triple of rows corresponding to a separate triangle.
The result of triangulate(x) is a single two-column matrix. The
rows are vertices of triangles, taken in non-overlapping triples.
signature(x = "gpc.poly", y =
"gpc.poly"): Combine all contours of two "gpc.poly"
objects and return the combined polygon as a "gpc.poly"
object.
signature(object = "gpc.poly"): Compute and
return the sum of the areas of all contours in a "gpc.poly"
object.
signature(x = "gpc.poly"): Scale (divide)
the x and y coordinates of a "gpc.poly" object by the
amount xscale and yscale, respectively. Return a
scaled "gpc.poly" object.
signature(object = "gpc.poly"): Return the
list of x and y coordinates of the vertices of a "gpc.poly"
object.
signature(x = "gpc.poly"): Return the
bounding box for a "gpc.poly" object.
signature(x = "gpc.poly"): Return a tristrip
list for a "gpc.poly" object.
signature(x = "gpc.poly"): Return a matrix
of vertices of a triangulation of a "gpc.poly" object.
Roger D. Peng; GPC Library by Alan Murta; tristrip additions by Duncan Murdoch
"gpc.poly" class documentation.
holepoly <- read.polyfile(system.file("poly-ex-gpc/hole-poly.txt",
package ="rgeos"), nohole = FALSE)
area.poly(holepoly)
stopifnot(area.poly(holepoly) == 8)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.