[R-sig-Geo] st_intersection produce Geometry type: GEOMETRY instead of Geometry type: POLYGON

[Marcelino de la Cruz Rot]

g_25000_c_polygons_only <- g_25000_c[st_is(x = g_25000_c, type = "POLYGON"),] # with a comma


El 10/02/2023 a las 21:33, Manuel Spínola escribió:
> Thnak you very much Bede-Fazekas.
>
> I got the following error:
>
> g_25000_c_polygons_only <- g_25000_c[st_is(x = g_25000_c, type = "POLYGON")]
>
> Error in `[.data.frame`(x, i) : undefined columns selected
>
> El vie, 10 feb 2023 a las 11:53, Bede-Fazekas Ákos (<bfalevlist using gmail.com>)
> escribió:
>
>> 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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>>
>

-- 
Marcelino de la Cruz Rot
Coordinador funcional de Biología
Depto. de Biología y Geología
Física y Química Inorgánica
Universidad Rey Juan Carlos
Móstoles España