xarray.Dataset.xvec.to_crs

Dataset.xvec.to_crs(variable_crs=None, **variable_crs_kwargs)

Transform shapely.Geometry objects of a variable to a new coordinate reference system.

Returns a new object with all the original data in addition to the transformed variable. The CRS the current array must be set using GeometryIndex.

This method will transform all points in all objects. It has no notion or projecting entire geometries. All segments joining points are assumed to be lines in the current projection, not geodesics. Objects crossing the dateline (or other projection boundary) will have undesirable behavior.

Parameters

variable_crsdict-like or None, optional

A dict where the keys are the names of the coordinates and values target CRS in any format accepted by pyproj.CRS.from_user_input() such as an authority string (e.g. "EPSG:4326"), EPSG code (e.g. 4326) or a WKT string.

**variable_crs_kwargsoptional

The keyword arguments form of variable_crs. One of variable_crs or variable_crs_kwargs must be provided.

Returns

assignedsame type as caller

A new object with the variables transformed to target CRSs.

See also

set_crs

Notes

Currently supports only xarray.Variable objects that are set as coordinates with GeometryIndex assigned. The implementation currently wraps Dataset.assign_coords or DataArray.assign_coords.

Examples

Transform coordinates backed by GeometryIndex from EPSG:4326 to ESPG:3857.

>>> da = (
...     xr.DataArray(
...         np.random.rand(2),
...         coords={"geom": [shapely.Point(1, 2), shapely.Point(3, 4)]},
...         dims="geom",
...     )
...     .xvec.set_geom_indexes("geom", crs=4326)
... )
>>> da
<xarray.DataArray (geom: 2)>
array([0.47575118, 0.09271935])
Coordinates:
  * geom     (geom) object POINT (1 2) POINT (3 4)
Indexes:
    geom     GeometryIndex (crs=EPSG:4326)
>>> da.xvec.to_crs(geom=3857)
<xarray.DataArray (geom: 2)>
array([0.47575118, 0.09271935])
Coordinates:
  * geom     (geom) object POINT (111319.49079327357 222684.20850554405) POIN...
Indexes:
    geom     GeometryIndex (crs=EPSG:3857)

The same can be done using dictionary arguments.

>>> da.xvec.to_crs({"geom": 3857})
<xarray.DataArray (geom: 2)>
array([0.47575118, 0.09271935])
Coordinates:
* geom     (geom) object POINT (111319.49079327357 222684.20850554405) POIN...
Indexes:
    geom     GeometryIndex (crs=EPSG:3857)

The same applies to a xarray.Dataset.

>>> ds = (
...     xr.Dataset(coords={"geom": [shapely.Point(1, 2), shapely.Point(3, 4)]})
...     .xvec.set_geom_indexes("geom", crs=4326)
... )
>>> ds
<xarray.Dataset>
Dimensions:  (geom: 2)
Coordinates:
* geom     (geom) object POINT (1 2) POINT (3 4)
Data variables:
    *empty*
Indexes:
    geom     GeometryIndex (crs=EPSG:4326)
>>> ds.xvec.to_crs(geom=3857)
<xarray.Dataset>
Dimensions:  (geom: 2)
Coordinates:
  * geom     (geom) object POINT (111319.49079327357 222684.20850554405) POIN...
Data variables:
    *empty*
Indexes:
    geom     GeometryIndex (crs=EPSG:3857)