R: Transform or convert coordinates of simple features directly...

st_transform_proj {lwgeom} | R Documentation

## 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")

[Package lwgeom version 0.2-7 Index]