Extend returns an Raster* object with a larger spatial extent. The output Raster object has the outer minimum and maximum coordinates of the input Raster and Extent arguments. Thus, all of the cells of the original raster are included. See
crop if you (also) want to remove rows or columns.
There is also an extend method for Extent objects to enlarge (or reduce) an Extent. You can also use algebraic notation to do that (see examples)
This function, "extend" replaces the obsolete function "expand" (to avoid a name conflict with the Matrix package).
## S3 method for class 'Raster': extend(x, y, value=NA, filename='', ...) ## S3 method for class 'Extent': extend(x, y, ...)
- Raster or Extent object
xis a Raster object,
yshould be an Extent object, or any object that is or has an Extent object, or an object from which it can be extracted (such as sp objects). Alternatively, you can provide a vector of length 2 with the
- value to assign to new cells
- Character (optional)
- Additional arguments as for
- RasterLayer or RasterBrick, or Extent
r <- raster(xmn=-150, xmx=-120, ymx=60, ymn=30, ncol=36, nrow=18) r <- 1:ncell(r) e <- extent(-180, 0, 0, 90) re <- extend(r, e) # expand with a number of rows and columns (at each side) re2 <- extend(r, c(2,10)) # Extent object e <- extent(r) e extend(e, 10) extend(e, 10, -10, 0, 20) e + 10 e * 2