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,
Ákos
___________
Ákos Bede-Fazekas
Centre for Ecological Research, Hungary
2023.02.10. 18:32 keltezéssel, Manuel Spínola írta:
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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