[R-sig-Geo] crop by pixel

Robert Hijmans r.hijmans at gmail.com
Wed Jul 27 21:41:43 CEST 2011

>> I need to crop a raster by pixel value, from upper X,Y left. 
>> I'm using this: 
>> spot <- raster(.........) 
>> x_shift <- 2 
>> y_shift <- 2 
>> crop(spot,extent(xmin(spot)+res(spot)[1]*x_shift,xmax(spot),ymin(spot),ymax(spot)-res(spot)[2]*y_shift)) 
>> It works, but is there another way? 

>A little bit less verbose: 
>x <- crop( spot, extent(spot, x_shift, nrow(spot), y_shift, ncol(spot)) ) 
>For smaller raster files, you could also consider (notice the drop=FALSE
>x <- spot[x_shift:nrow(spot), y_shift:ncol(spot),  drop=FALSE] 

In the above I made a mistake: I reversed x_shift and y_shift. It should be:

x <- crop( spot, extent(spot, y_shift, nrow(spot), x_shift, ncol(spot)) ) 

x <- spot[y_shift:nrow(spot), x_shift:ncol(spot),  drop=FALSE] 


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