[R-sig-Geo] raster::clump not working?

[Bede-Fazekas Ákos]

Dear Joao,
I think function clump() works as it should be. A toy example:
x <- raster(matrix(sample(x = c(NA, NA, NA, 1), size = 36*18, replace = 
TRUE), ncol=36, nrow=18))
plot(x)
plot(clump(x))

Maybe you are searching for a function that aggregate those cells that 
have the same value?
In this case it would do what you want (I'm sure there is a more 
straightforward way...):
r <- raster(ncols=36, nrows=18)
x <- init(r, fun='cell')
y <- layerize(x)
ids <- calc(x = y, fun = function(layers) 
{return(which(as.logical(layers))[1])})
plot(ids)

HTH,
Ákos Bede-Fazekas
Hungarian Academy of Sciences


2018.05.25. 12:00 keltezéssel, João Carreiras írta:
> Hi!
>
> I've been trying to run the clump command but the output is consistently a
> raster with values == 1. Please find below an example.
>
> I'm sure I'm doing something stupid. However, the command is really
> straightforward and I can't seem to identify what the problem might be.
>
> Any help really appreciated.
> Thanks
> Joao
>
> r <- raster(ncols=36, nrows=18)
> x <- init(r, fun='cell')
> x
> class       : RasterLayer
> dimensions  : 18, 36, 648  (nrow, ncol, ncell)
> resolution  : 10, 10  (x, y)
> extent      : -180, 180, -90, 90  (xmin, xmax, ymin, ymax)
> coord. ref. : +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0
> data source : in memory
> names       : layer
> values      : 1, 648  (min, max)
> a <- clump(x)
> a
> class       : RasterLayer
> dimensions  : 18, 36, 648  (nrow, ncol, ncell)
> resolution  : 10, 10  (x, y)
> extent      : -180, 180, -90, 90  (xmin, xmax, ymin, ymax)
> coord. ref. : +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0
> data source : in memory
> names       : clumps
> values      : 1, 1  (min, max)
>
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