Get, set, or replace geometry from an sf object

# S3 method for sfc
st_geometry(obj, ...)

st_geometry(obj, ...)

# S3 method for sf
st_geometry(obj, ...)

# S3 method for sfc
st_geometry(obj, ...)

# S3 method for sfg
st_geometry(obj, ...)

st_geometry(x) <- value

st_set_geometry(x, value)

st_drop_geometry(x)

Arguments

obj	object of class `sf` or `sfc`
...	ignored
x	object of class `data.frame`
value	object of class `sfc`, or `character`

Value

st_geometry returns an object of class sfc, a list-column with geometries

st_geometry returns an object of class sfc. Assigning geometry to a data.frame creates an sf object, assigning it to an sf object replaces the geometry list-column.

Details

when applied to a data.frame and when value is an object of class sfc, st_set_geometry and st_geometry<- will first check for the existence of an attribute sf_column and overwrite that, or else look for list-columns of class sfc and overwrite the first of that, or else write the geometry list-column to a column named geometry. In case value is character and x is of class sf, the "active" geometry column is set to x[[value]].

the replacement function applied to sf objects will overwrite the geometry list-column, if value is NULL, it will remove it and coerce x to a data.frame.

st_drop_geometry drops the geometry of its argument, and reclasses it accordingly

Examples

df = data.frame(a = 1:2)
sfc = st_sfc(st_point(c(3,4)), st_point(c(10,11)))
st_geometry(sfc)
#> Geometry set for 2 features 
#> geometry type:  POINT
#> dimension:      XY
#> bbox:           xmin: 3 ymin: 4 xmax: 10 ymax: 11
#> CRS:            NA
#> POINT (3 4)
#> POINT (10 11)
st_geometry(df) <- sfc
class(df)
#> [1] "sf"         "data.frame"
st_geometry(df)
#> Geometry set for 2 features 
#> geometry type:  POINT
#> dimension:      XY
#> bbox:           xmin: 3 ymin: 4 xmax: 10 ymax: 11
#> CRS:            NA
#> POINT (3 4)
#> POINT (10 11)
st_geometry(df) <- sfc # replaces
st_geometry(df) <- NULL # remove geometry, coerce to data.frame
sf <- st_set_geometry(df, sfc) # set geometry, return sf
st_set_geometry(sf, NULL) # remove geometry, coerce to data.frame
#>   a
#> 1 1
#> 2 2