st_intersection produce Geometry type: GEOMETRY instead of Geometry type: POLYGON

Manuel, I think you're looking for an intersect*s* rather than the
intersection. Is the following what you're after?


nc = st_read(system.file("shape/nc.shp", package="sf"))
nc <- st_transform(nc, 3857)
g_50000 <- st_make_grid(nc, cellsize = 50000) |> st_as_sf()
g_50000 <- g_50000[nc, ]
g_50000_d <- st_union(g_50000)
g_25000 = st_make_grid(g_50000_d, cellsize = 25000) |> st_as_sf()
g_25000 # Geometry type: POLYGON

index <- which(lengths(st_intersects(g_50000, nc)) > 0)
plot(st_union(g_50000[index,]))

On Fri, Feb 10, 2023 at 12:53 PM Bede-Fazekas ?kos <bfalevlist at gmail.com>
wrote:

Dear Manuel,

technically, the result of st_intersection(x, y), where both x and y are
POLYGONs, can be POINT, LINESTRING, POLGYON and GEOMETRY as well. The
result is GEOMETRY if the type of the different features is not the same
(e.g. POLYGON+POINT).
You can subset the result in this way:
g_25000_c_polygons_only <- g_25000_c[st_is(x = g_25000_c, type =
"POLYGON")]

HTH,
?kos
___________
?kos Bede-Fazekas
Centre for Ecological Research, Hungary

2023.02.10. 18:32 keltez?ssel, Manuel Sp?nola ?rta:

Dear list members,

I am trying to "crop" a polygon (grid) with a polygon, but the result

is

an

sf object Geometry type: GEOMETRY, instead of an sf object Geometry

type:

POLYGON.

How can I obtain an sf POLYGON?

nc = st_read(system.file("shape/nc.shp", package="sf"))



nc <- st_transform(nc, 3857)



g_50000 <- st_make_grid(nc, cellsize = 50000) |> st_as_sf()



g_50000 <- g_50000[nc, ]



g_50000_d <- st_union(g_50000)



g_25000 = st_make_grid(g_50000_d, cellsize = 25000) |> st_as_sf()



g_25000 # Geometry type: POLYGON



g_25000_c <- st_intersection(g_25000, g_50000_d)



g_25000_c # Geometry type: GEOMETRY

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