sf (version 0.2-8)

st_as_sf: Convert foreign object to an sf object

Description

Convert foreign object to an sf object

Usage

st_as_sf(x, ...)
"st_as_sf"(x, ..., relation_to_geometry = NA_character_, coords, wkt, dim = "XYZ", remove = TRUE)
"st_as_sf"(x, ...)

Arguments

x

object to be converted into an object class sf

...

passed on to st_sf, might included crs

relation_to_geometry

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

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?

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_coordinates is FALSE.

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
data(meuse, package = "sp")
meuse_sf = st_as_sf(meuse, coords = c("x", "y"), crs = 28992, relation_to_geometry = "field")
meuse_sf[1:3,]
summary(meuse_sf)
library(sp)
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")
if (require("rgeos")) {
  r = createSPComment(SpatialPolygons(list(p1,p2)))
  comment(r)
  comment(r@polygons[[1]])
  scan(text = comment(r@polygons[[1]]), quiet = TRUE)
  library(sf)
  a = 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")))