Make duplicated and unique work (fixes #2138)

[bart1]

add a duplicated.sf method so unique and duplicated work with factor column in the data.frame

[bart1]

@edzer I guess the tic error is unrelated to the pull request right? or is there a way to prevent it?

[edzer]

That's right.

[edzer]

Thanks!

[jmaspons]

Does the function take into account the geometries to determine duplicated rows? I could not find any docs

[bart1]

Does the function take into account the geometries to determine duplicated rows? I could not find any docs

yes:

require(sf)
#> Loading required package: sf
#> Linking to GEOS 3.10.2, GDAL 3.4.1, PROJ 8.2.1; sf_use_s2() is TRUE
st_as_sf(data.frame(x=c(1,1),y=2), coords = 1:2) |> duplicated()
#> [1] FALSE  TRUE
st_as_sf(data.frame(x=c(1,3),y=2), coords = 1:2) |> duplicated()
#> [1] FALSE FALSE

^{Created on 2025-06-27 with reprex v2.1.1}