st_transform_proj {lwgeom}

Transform or convert coordinates of simple features directly with Proj.4 (bypassing GDAL)

Description

Transform or convert coordinates of simple features directly with Proj.4 (bypassing GDAL)

Usage

st_transform_proj(x, crs, ...)

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

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

## S3 method for class 'sfg'
st_transform_proj(x, crs, ...)

Arguments

x

object of class sf, sfc or sfg

crs

character; target CRS, or, in case of a length 2 character vector, source and target CRS

...

ignored

Details

Transforms coordinates of object to new projection, using PROJ directly rather than the GDAL API used by st_transform.

If crs is a single CRS, it forms the target CRS, and in that case the source CRS is obtained as st_crs(x). Since this presumes that the source CRS is accepted by GDAL (which is not always the case), a second option is to specify the source and target CRS as two proj4strings in argument crs. In the latter case, st_crs(x) is ignored and may well be NA.

The st_transform_proj method for sfg objects assumes that the CRS of the object is available as an attribute of that name.

Examples

library(sf)
p1 = st_point(c(7,52))
p2 = st_point(c(-30,20))
sfc = st_sfc(p1, p2, crs = 4326)
sfc
st_transform_proj(sfc, "+proj=wintri")
library(sf)
nc = st_read(system.file("shape/nc.shp", package="sf"))
st_transform_proj(nc[1,], "+proj=wintri +over")
st_transform_proj(structure(p1, proj4string = "+init=epsg:4326"), "+init=epsg:3857")