transform_xy: Transform geospatial x/y coordinates

In gdalraster: Bindings to 'GDAL'

Transform geospatial x/y coordinates

Description

transform_xy() transforms geospatial x, y coordinates to a new projection. The input points may optionally have z vertices (x, y, z) or time values (x, y, z, t). Wrapper for OGRCoordinateTransformation::Transform() in the GDAL Spatial Reference System C++ API.

Usage

transform_xy(pts, srs_from, srs_to)

Arguments

pts	A data frame or numeric matrix containing geospatial point coordinates, or point geometries as a list of WKB raw vectors or character vector of WKT strings. If data frame or matrix, the number of columns must be either two (x, y), three (x, y, z) or four (x, y, z, t). May be also be given as a numeric vector for one point (xy, xyz, or xyzt).
srs_from	Character string specifying the spatial reference system for pts. May be in WKT format or any of the formats supported by srs_to_wkt().
srs_to	Character string specifying the output spatial reference system. May be in WKT format or any of the formats supported by srs_to_wkt().

Value

Numeric matrix of geospatial (x, y) coordinates in the projection specified by srs_to (potentially also with z, or z and t columns).

Note

transform_xy() uses traditional GIS order for the input and output xy (i.e., longitude/latitude ordered for geographic coordinates).

Input points that contain missing values (NA) will be assigned NA in the output and a warning emitted. Input points that fail to transform with the GDAL API call will also be assigned NA in the output with a specific warning indicating that case.

See Also

srs_to_wkt(), inv_project()

Examples

pt_file <- system.file("extdata/storml_pts.csv", package="gdalraster")
pts <- read.csv(pt_file)
print(pts)
# id, x, y in NAD83 / UTM zone 12N
# transform to NAD83 / CONUS Albers
transform_xy(pts = pts[, -1], srs_from = "EPSG:26912", srs_to = "EPSG:5070")

gdalraster documentation built on June 8, 2025, 12:37 p.m.