CODEWITHSUNDEEP
rgisraster
gvan
gvan

Reputation: 523

Subset a raster using row/column index

When subsetting a matrix or DF, it is possible to reference row columns, such as df1[1:5, 3:10], or df3[2:4, ].

Is there any way to do this with a raster? That is, can I clip just rows 500:700, for example from a raster object?

I have tried using rasterFromCells(), but it doesn't give me the result I want (and it seems like there should be a more simple solution given R's other slick subsetting methods).

Example: 

r <- raster(ncols = 50, nrow = 50)
r[] <- 1:ncell(r)

# I would like to subset the bottom 50 rows of cells, but keep it as a raster.
# However, this returns a numeric object.
rSub <- r[30:50, 1:50]

Thanks!

Upvotes: 3

Views: 4060

Answers (2)

Robert Hijmans
Robert Hijmans

Reputation: 47071

I prefer using crop as shown by Seymour. There is another way, using drop=FALSE

library(raster)
r <- raster(ncols = 10, nrow = 10)
values(r) <- 1:ncell(r)

rSub <- r[3:5, 2:3, drop=FALSE] 
rSub
#class       : RasterLayer 
#dimensions  : 3, 2, 6  (nrow, ncol, ncell)
#resolution  : 36, 18  (x, y)
#extent      : -144, -72, 0, 54  (xmin, xmax, ymin, ymax)
#coord. ref. : +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0 
#source      : memory
#names       : layer 
#values      : 22, 43  (min, max)

Upvotes: 4

Seymour
Seymour

Reputation: 3264

I don't find the question very clear.

However, is this what you are looking for?

subR <- crop(r, extent(r, 30, 50, 1, 50))

plot(subR)

The function crop() of raster package does the trick because allow you to subset the raster object using rows and columns.

Upvotes: 11

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