# polygrid: Coordinates of Points Inside a Polygon In StatDA: Statistical Analysis for Environmental Data

 polygrid R Documentation

## Coordinates of Points Inside a Polygon

### Description

This function builds a rectangular grid and extracts points which are inside of an internal polygonal region.

### Usage

polygrid(xgrid, ygrid, borders, vec.inout = FALSE, ...)


### Arguments

 xgrid grid values in the x-direction. ygrid grid values in the y-direction. borders a matrix with polygon coordinates defining the borders of the region. vec.inout logical. If TRUE a logical vector is included in the output indicating whether each point of the grid is inside the polygon. Defaults to FALSE. ... currently not used (kept for back compatibility).

### Details

The function works as follows: First it creates a grid using the R function expand.grid and then it uses the geoR' internal function .geoR_inout() which wraps usage of SpatialPoints and over from the package sp to extract the points of the grid which are inside the polygon.

### Value

A list with components:

 xypoly an n \times 2 matrix with the coordinates of the points inside the polygon. vec.inout logical, a vector indicating whether each point of the rectangular grid is inside the polygon. Only returned if vec.inout = TRUE.

### Author(s)

Paulo Justiniano Ribeiro Jr. paulojus@leg.ufpr.br,
Peter J. Diggle p.diggle@lancaster.ac.uk.

### References

See the package geoR.

expand.grid, over, SpatialPoints.

### Examples

 poly <- matrix(c(.2, .8, .7, .1, .2, .1, .2, .7, .7, .1), ncol=2)
plot(0:1, 0:1, type="n")
lines(poly)
poly.in <- polygrid(seq(0,1,l=11), seq(0,1,l=11), poly, vec=TRUE)
points(poly.in\$xy)


StatDA documentation built on June 7, 2023, 6:26 p.m.