[R-sig-Geo] cleaning up a SpatialGridDataFrame

[Robert Hijmans]

> I have an image which is a SpatialGridDatafFrame. This image has a number
of 
> cells that i need to erase or to delete but i don`t know how to do this in
> R. 

Mary,

It is not clear what you mean with "erase or delete". 

If you refer to setting some cell values to NA you can do, with
SpatialGridDataFrame x, things like
x at data[2:5,] <- NA

or make a RasterLayer

library(raster)
r <- raster(x)
x[2:5] <- NA
x[1:2, 1:2] <- NA

or use raster package functions like 'reclass', 'subs', or 'cut'

If you refer to removing entire rows or columns from your grid, you can use
function 'crop' and perhaps 'trim' 

Robert


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