xarray.where¶
-
xarray.
where
(cond, x, y)¶ Return elements from x or y depending on cond.
Performs xarray-like broadcasting across input arguments.
- Parameters
cond (scalar, array, Variable, DataArray or Dataset with boolean dtype) – When True, return values from x, otherwise returns values from y.
x (scalar, array, Variable, DataArray or Dataset) – values to choose from where cond is True
y (scalar, array, Variable, DataArray or Dataset) – values to choose from where cond is False
dimension coordinates on these objects must be aligned with each (All) –
and with cond. (other) –
- Returns
In priority order (Dataset, DataArray, Variable or array, whichever)
type appears as an input argument.
Examples
>>> import xarray as xr >>> import numpy as np >>> x = xr.DataArray( ... 0.1 * np.arange(10), ... dims=["lat"], ... coords={"lat": np.arange(10)}, ... name="sst", ... ) >>> x <xarray.DataArray 'sst' (lat: 10)> array([0. , 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9]) Coordinates: * lat (lat) int64 0 1 2 3 4 5 6 7 8 9
>>> xr.where(x < 0.5, x, x * 100) <xarray.DataArray 'sst' (lat: 10)> array([ 0. , 0.1, 0.2, 0.3, 0.4, 50. , 60. , 70. , 80. , 90. ]) Coordinates: * lat (lat) int64 0 1 2 3 4 5 6 7 8 9
>>> y = xr.DataArray( ... 0.1 * np.arange(9).reshape(3, 3), ... dims=["lat", "lon"], ... coords={"lat": np.arange(3), "lon": 10 + np.arange(3)}, ... name="sst", ... ) >>> y <xarray.DataArray 'sst' (lat: 3, lon: 3)> array([[0. , 0.1, 0.2], [0.3, 0.4, 0.5], [0.6, 0.7, 0.8]]) Coordinates: * lat (lat) int64 0 1 2 * lon (lon) int64 10 11 12
>>> xr.where(y.lat < 1, y, -1) <xarray.DataArray (lat: 3, lon: 3)> array([[ 0. , 0.1, 0.2], [-1. , -1. , -1. ], [-1. , -1. , -1. ]]) Coordinates: * lat (lat) int64 0 1 2 * lon (lon) int64 10 11 12
>>> cond = xr.DataArray([True, False], dims=["x"]) >>> x = xr.DataArray([1, 2], dims=["y"]) >>> xr.where(cond, x, 0) <xarray.DataArray (x: 2, y: 2)> array([[1, 2], [0, 0]]) Dimensions without coordinates: x, y