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

[Manuel Spínola]

Thank you very much Josiah.

If I ran the code you suggested me, How I get the g_25000 object (a grid)?

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



El vie, 10 feb 2023 a las 12:10, Josiah Parry (<josiah.parry using gmail.com>)
escribió:

> 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 Ákos <bfalevlist using 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,
> > 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
> > >
> > >
> > >
> > >
> >
> > _______________________________________________
> > R-sig-Geo mailing list
> > R-sig-Geo using r-project.org
> > https://stat.ethz.ch/mailman/listinfo/r-sig-geo
> >
>
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-- 
*Manuel Spínola, Ph.D.*
Instituto Internacional en Conservación y Manejo de Vida Silvestre
Universidad Nacional
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<http://www.icomvis.una.ac.cr/index.php/manuel>
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