Create simple feature geometry list column

Source: R/sfc.R

Create simple feature geometry list column, set class, and add coordinate reference system and precision. For data.frame alternatives see st_sf(). To convert a foreign object to sfc, see st_as_sfc()

st_sfc(
  ...,
  crs = NA_crs_,
  precision = 0,
  check_ring_dir = FALSE,
  dim,
  recompute_bbox = FALSE,
  oriented = NA
)

# S3 method for class 'sfc'
x[i, j, ..., op = st_intersects]

Arguments

...

zero or more simple feature geometries (objects of class sfg), or a single list of such objects; NULL values will get replaced by empty geometries.

crs

coordinate reference system: integer with the EPSG code, or character with proj4string

precision

numeric; see st_as_binary

check_ring_dir

see st_read

dim

character; if this function is called without valid geometries, this argument may carry the right dimension to set empty geometries

recompute_bbox

logical; use TRUE to force recomputation of the bounding box

oriented

logical; if TRUE, the ring is oriented such that left of the edges is inside the polygon; this is needed for convering polygons larger than half the globe to s2

x

object of class sfc

i

record selection. Might also be an sfc/sf object to work with the op argument

j

ignored if op is specified

op

function, geometrical binary predicate function to apply when i is a sf/sfc object. Additional arguments can be specified using ..., see examples.

Value

an object of class sfc, which is a classed list-column with simple feature geometries.

Details

A simple feature geometry list-column is a list of class c("stc_TYPE", "sfc") which most often contains objects of identical type; in case of a mix of types or an empty set, TYPE is set to the superclass GEOMETRY.

if x has a dim attribute (i.e. is an array or matrix) then op cannot be used.

Examples

pt1 = st_point(c(0,1))
pt2 = st_point(c(1,1))
(sfc = st_sfc(pt1, pt2))
#> Geometry set for 2 features 
#> Geometry type: POINT
#> Dimension:     XY
#> Bounding box:  xmin: 0 ymin: 1 xmax: 1 ymax: 1
#> CRS:           NA
#> POINT (0 1)
#> POINT (1 1)
sfc[sfc[1], op = st_is_within_distance, dist = 0.5]
#> Geometry set for 1 feature 
#> Geometry type: POINT
#> Dimension:     XY
#> Bounding box:  xmin: 0 ymin: 1 xmax: 0 ymax: 1
#> CRS:           NA
#> POINT (0 1)
d = st_sf(data.frame(a=1:2, geom=sfc))