[R-sig-Geo] Clipping problem

[Peter Larson]

Hello all,

I have a grid of points and a spatial polygon shape file. I want to
clip the grid so that I only have the point which lie within the
shapefile.

I tried the following code:

## create a grid onto which we will interpolate:
## first get the range in data
x.range <- c(37,50)
y.range <- c(29,38)

## now expand to a grid with 500 meter spacing:
grd <- expand.grid(x=seq(from=x.range[1], to=x.range[2], by=.01),
y=seq(from=y.range[1], to=y.range[2], by=.01) )

## convert to SpatialPixel class
coordinates(grd) <- ~ x+y
gridded(grd) <- TRUE

## Read in Shapefile
ccShapet=readShapePoly('IRQ_adm0') # here cbg00barncnty is an ArcGIS shapefile

## Clip
clip <- overlay(grd, ccShapet)

#Plot
plot(clip)

BUT it does not work. I just get a vector of number and NA's, but not
the clipped grid.

Any ideas?

Thanks

Pete