# polygrid

##### Coordinates of Points Inside a Polygon

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

- Keywords
- spatial

##### 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.

Within the package geoR
this function is typically used to select points in a non-rectangular
region to perform spatial prediction
using `krige.bayes`

, `krige.conv`

or
`ksline`

. It is also useful to produce
image or perspective plots of the prediction results.

##### Value

A list with components:

an \(n \times 2\) matrix with the coordinates of the points inside the polygon.

logical, a vector indicating whether each point of
the rectangular grid is inside the polygon. Only returned if `vec.inout = TRUE`

.

##### References

Further information on the package geoR can be found at: http://www.leg.ufpr.br/geoR.

##### See Also

##### Examples

```
# NOT RUN {
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)
# }
```

*Documentation reproduced from package geoR, version 1.8-1, License: GPL (>= 2)*