xarray.where (original) (raw)

xarray.where(cond, x, y, keep_attrs=None)[source]#

Return elements from x or y depending on cond.

Performs xarray-like broadcasting across input arguments.

All dimension coordinates on x and y must be aligned with each other and with cond.

Parameters:

• cond (scalar, array, Variable, DataArray or Dataset) – 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
• keep_attrs (bool or str or callable(), optional) – How to treat attrs. If True, keep the attrs of x.

Returns:

Dataset, DataArray, Variable or array – In priority order: Dataset, DataArray, Variable or array, whichever type appears as an input argument.

Examples

x = xr.DataArray( ... 0.1 * np.arange(10), ... dims=["lat"], ... coords={"lat": np.arange(10)}, ... name="sst", ... ) x <xarray.DataArray 'sst' (lat: 10)> Size: 80B array([0. , 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9]) Coordinates:

• lat (lat) int64 80B 0 1 2 3 4 5 6 7 8 9

xr.where(x < 0.5, x, x * 100) <xarray.DataArray 'sst' (lat: 10)> Size: 80B array([ 0. , 0.1, 0.2, 0.3, 0.4, 50. , 60. , 70. , 80. , 90. ]) Coordinates:

• lat (lat) int64 80B 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)> Size: 72B array([[0. , 0.1, 0.2], [0.3, 0.4, 0.5], [0.6, 0.7, 0.8]]) Coordinates:

• lat (lat) int64 24B 0 1 2
• lon (lon) int64 24B 10 11 12

xr.where(y.lat < 1, y, -1) <xarray.DataArray (lat: 3, lon: 3)> Size: 72B array([[ 0. , 0.1, 0.2], [-1. , -1. , -1. ], [-1. , -1. , -1. ]]) Coordinates:

• lat (lat) int64 24B 0 1 2
• lon (lon) int64 24B 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)> Size: 32B array([[1, 2], [0, 0]]) Dimensions without coordinates: x, y