# new-generics {rgeos}

### Description

Some generic functions and methods for polygon objects

### Usage

append.poly(x, y) area.poly(object, ...) get.pts(object) get.bbox(x) scale.poly(x, ...) tristrip(x) triangulate(x)

### Arguments

- x,object
- A polygon object
- y
- A polygon object
- ...
- Other arguments passed to methods

### Details

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.

### Methods

- append.poly
`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.- area.poly
`signature(object = "gpc.poly")`

: Compute and return the sum of the areas of all contours in a`"gpc.poly"`

object.- scale.poly
`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.- get.pts
`signature(object = "gpc.poly")`

: Return the list of x and y coordinates of the vertices of a`"gpc.poly"`

object.- get.bbox
`signature(x = "gpc.poly")`

: Return the bounding box for a`"gpc.poly"`

object.- tristrip
`signature(x = "gpc.poly")`

: Return a tristrip list for a`"gpc.poly"`

object.- triangulate
`signature(x = "gpc.poly")`

: Return a matrix of vertices of a triangulation of a`"gpc.poly"`

object.

### See Also

`"gpc.poly"`

class documentation.

### Examples

holepoly <- read.polyfile(system.file("poly-ex-gpc/hole-poly.txt", package ="rgeos"), nohole = FALSE) area.poly(holepoly) stopifnot(area.poly(holepoly) == 8)

Documentation reproduced from package rgeos, version 0.3-3. License: GPL (>= 2)