st_as_sf: Convert foreign object to an sf object

In sf: Simple Features for R

Convert foreign object to an sf object

Description

Convert foreign object to an sf object

Usage

st_as_sf(x, ...)

## S3 method for class 'data.frame'
st_as_sf(
  x,
  ...,
  agr = NA_agr_,
  coords,
  wkt,
  dim = "XYZ",
  remove = TRUE,
  na.fail = TRUE,
  sf_column_name = NULL
)

## S3 method for class 'sf'
st_as_sf(x, ...)

## S3 method for class 'sfc'
st_as_sf(x, ...)

## S3 method for class 'Spatial'
st_as_sf(x, ...)

## S3 method for class 'map'
st_as_sf(x, ..., fill = TRUE, group = TRUE)

## S3 method for class 'ppp'
st_as_sf(x, ...)

## S3 method for class 'psp'
st_as_sf(x, ...)

## S3 method for class 'lpp'
st_as_sf(x, ...)

## S3 method for class 's2_geography'
st_as_sf(x, ..., crs = st_crs(4326))

Arguments

x	object to be converted into an object class sf
...	passed on to st_sf, might included named arguments crs or precision
agr	character vector; see details section of st_sf
coords	in case of point data: names or numbers of the numeric columns holding coordinates
wkt	name or number of the character column that holds WKT encoded geometries
dim	specify what 3- or 4-dimensional points reflect: passed on to st_point (only when argument coords is given)
remove	logical; when coords or wkt is given, remove these columns from data.frame?
na.fail	logical; if TRUE, raise an error if coordinates contain missing values
sf_column_name	character; name of the active list-column with simple feature geometries; in case there is more than one and sf_column_name is NULL, the first one is taken.
fill	logical; the value for fill that was used in the call to map.
group	logical; if TRUE, group id labels from map by their prefix before :
crs	coordinate reference system to be assigned; object of class crs

Details

setting argument wkt annihilates the use of argument coords. If x contains a column called "geometry", coords will result in overwriting of this column by the sfc geometry list-column. Setting wkt will replace this column with the geometry list-column, unless remove is FALSE.

If coords has length 4, and dim is not XYZM, the four columns are taken as the xmin, ymin, xmax, ymax corner coordinates of a rectangle, and polygons are returned.

Examples

pt1 = st_point(c(0,1))
pt2 = st_point(c(1,1))
st_sfc(pt1, pt2)
d = data.frame(a = 1:2)
d$geom = st_sfc(pt1, pt2)
df = st_as_sf(d)
d$geom = c("POINT(0 0)", "POINT(0 1)")
df = st_as_sf(d, wkt = "geom")
d$geom2 = st_sfc(pt1, pt2)
st_as_sf(d) # should warn
if (require(sp, quietly = TRUE)) {
 data(meuse, package = "sp")
 meuse_sf = st_as_sf(meuse, coords = c("x", "y"), crs = 28992, agr = "constant")
 meuse_sf[1:3,]
 summary(meuse_sf)
}
if (require(sp, quietly = TRUE)) {
x = rbind(c(-1,-1), c(1,-1), c(1,1), c(-1,1), c(-1,-1))
x1 = 0.1 * x + 0.1
x2 = 0.1 * x + 0.4
x3 = 0.1 * x + 0.7
y = x + 3
y1 = x1 + 3
y3 = x3 + 3
m = matrix(c(3, 0), 5, 2, byrow = TRUE)
z = x + m
z1 = x1 + m
z2 = x2 + m
z3 = x3 + m
p1 = Polygons(list( Polygon(x[5:1,]), Polygon(x2), Polygon(x3),
   Polygon(y[5:1,]), Polygon(y1), Polygon(x1), Polygon(y3)), "ID1")
p2 = Polygons(list( Polygon(z[5:1,]), Polygon(z2), Polygon(z3), Polygon(z1)),
  "ID2")
r = SpatialPolygons(list(p1,p2))
a = suppressWarnings(st_as_sf(r))
summary(a)
demo(meuse, ask = FALSE, echo = FALSE)
summary(st_as_sf(meuse))
summary(st_as_sf(meuse.grid))
summary(st_as_sf(meuse.area))
summary(st_as_sf(meuse.riv))
summary(st_as_sf(as(meuse.riv, "SpatialLines")))
pol.grd = as(meuse.grid, "SpatialPolygonsDataFrame")
# summary(st_as_sf(pol.grd))
# summary(st_as_sf(as(pol.grd, "SpatialLinesDataFrame")))
}
if (require(spatstat.geom)) {
  g = st_as_sf(gorillas)
  # select only the points:
  g[st_is(g, "POINT"),]
}
if (require(spatstat.linnet)) {
 data(chicago)
 plot(st_as_sf(chicago)["label"])
 plot(st_as_sf(chicago)[-1,"label"])
}

sf documentation built on Oct. 11, 2024, 9:08 a.m.