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I need to crop a raster (RasterLayer or RasterStack) to get a specific number of pixels in X and Y.

Let's imagine that we have a raster r with ncol(r)=6 and nrow(r)=11. I need to get a raster with 1st to 5th pixels in X (ncol=5) and 1st to 10th in Y (nrow=10). So dim(r) = 10 5 1

I have managed to do this by converting the raster into a matrix, but I need to keep the RasterLayer or RasterStack object.

r <- raster(nrow=11, ncol=6)
values(r) <- 1:ncell(r)

r

> r
class      : RasterLayer 
dimensions : 11, 6, 66  (nrow, ncol, ncell)
resolution : 60, 16.36364  (x, y)
extent     : -180, 180, -90, 90  (xmin, xmax, ymin, ymax)
crs        : +proj=longlat +datum=WGS84 +no_defs 
source     : memory
names      : layer 
values     : 1, 66  (min, max)

r <- as.matrix(r)
r <- r[1:10, 1:5]

r

> r
      [,1] [,2] [,3] [,4] [,5]
 [1,]    1    2    3    4    5
 [2,]    7    8    9   10   11
 [3,]   13   14   15   16   17
 [4,]   19   20   21   22   23
 [5,]   25   26   27   28   29
 [6,]   31   32   33   34   35
 [7,]   37   38   39   40   41
 [8,]   43   44   45   46   47
 [9,]   49   50   51   52   53
[10,]   55   56   57   58   59
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1 Answer 1

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You can use crop from package raster. If you want rows from 1 to 10 and columns from 1 to 5 this is the code.

rc <- crop(r, extent(r, 1, 10, 1, 5))
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2
  • Fantastic! Thank you
    – sermomon
    Commented Oct 7, 2021 at 11:33
  • 2
    Took me a second to see how this wasn't cropping at coordinate values rather than row/col values, but its passing r as the first argument to extent that does this. Without r you'd get those coordinates. Neat.
    – Spacedman
    Commented Oct 7, 2021 at 17:59

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