Transform or convert coordinates of a simple feature or bounding box object

This function wraps sf::st_transform() but supports a wider range of input objects and, using the as_sf_class() function, returns a wider range of objects. Typically, takes a sf, sfc, or bbox object and transform to coordinate reference system to match the value of crs or the object provided to crs. If x is a data.frame or if x is NULL and allow_null is TRUE (defaults to FALSE) it is returned as is.

Usage

st_transform_ext(
  x,
  crs = NULL,
  class = NULL,
  rotate = 0,
  allow_null = FALSE,
  allow_list = TRUE
)

st_omerc(x, rotate = 0)

st_wgs84(x)

Arguments

x

An sf, sfc, or bbox object, a list of sf objects, or a data.frame object (always returned as is).

crs

A character or numeric reference to a coordinate reference system supported by sf::st_crs() or another sf, sfc, or bbox object that is used to provide crs.

class

Class of object to return (sf or bbox). If x is an sf list, the returned object remains a list but may be converted to bbox if class = "sf".

rotate

If rotate is greater or less than 0, st_transform_ext() calls st_omerc() and returns an object with the Oblique Mercator projection passing the value of rotate to the gamma parameter of the projection. rotate must be between -45 and 45 degrees.

allow_null

If TRUE and x is NULL return x without an error. Defaults to FALSE.

allow_list

If TRUE, x can be a list of sf, sfc, or bbox objects. If FALSE, only sf, sfc, or bbox objects are supported. Defaults to TRUE.

Value

An sf, sfc, or bbox object transformed to a new coordinate reference system.

See also

sf::st_transform(),sf::st_crs()

Examples

nc <- sf::read_sf(system.file("shape/nc.shp", package = "sf"))

nc_bbox <- sf::st_bbox(nc)

nc_3857 <- st_transform_ext(nc, 3857)

st_transform_ext(nc_bbox, crs = 4326)
#>      xmin      ymin      xmax      ymax 
#> -84.32379  33.88210 -75.45656  36.58981 

sf::st_crs(st_transform_ext(nc_3857, crs = nc))$input
#> [1] "NAD27"

sf::st_crs(st_wgs84(nc_3857))$input
#> [1] "EPSG:4326"