patches() returns unexpected results

[Nowosad]

I tried to use patches() recently. It works well on the example code from the help file, but returns only one patch on various of my own data. Do I misunderstand the function or is there a bug there?

library(terra)
#> terra 1.5.13
checker_values = rep(c(rep(c(1, 2), 8), rep(c(2, 1), 8)), 8)

checker_map = rast(ncol = 16, nrow = 16, resolution = 1,
                   xmin = 0, xmax = 16, ymin = 0, ymax = 16,
                   vals = checker_values)

plot(checker_map)

plot(patches(checker_map))

^{Created on 2022-01-20 by the reprex package (v2.0.1)}

Session info

sessioninfo::session_info()
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[rhijmans]

patches detects patches (connect cells that have any value) surrounded by NA (or zero).
You assume that it detects patches of cells surrounded by cells with any other value.
That is not unreasonable. I will have look.

[aloboa]

Please open and modify as suggested by Nowosad, it would be much more useful.

[rhijmans]

You can now use

plot(patches(checker_map, 8, values=T))

[aloboa]

While this works,

library(RStoolbox)
> library(terra)
terra 1.8.3
> dim(lsat)
[1] 310 287       7
klsat <- k_means(lsat, centers=4, maxcell=10000)
plot(klsat,col=map.pal("random"))
a <- patches(klsat, values=TRUE)
plot(a, col=map.pal("random"))

Using a larger image crashes a system with 64 GB of RAM:

lsat2 <- disagg(lsat,8)
dim(lsat2)
[1] 2480 2296       7
klsat2 <- k_means(lsat2, centers=4, maxcell=10000)
plot(klsat2,col=map.pal("random"))
a <- patches(klsat2, values=TRUE)