Function where

xarray/computation/computation.py:682–832

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 Data

(cond, x, y, keep_attrs=None)

def where(cond, x, y, keep_attrs=None):
    """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 {"drop", "identical", "no_conflicts", "drop_conflicts", "override"} or callable, optional

        - 'override' or True (default): skip comparing and copy attrs from `x` to the result.
        - 'drop' or False: empty attrs on returned xarray object.
        - 'identical': all attrs must be the same on every object.
        - 'no_conflicts': attrs from all objects are combined, any that have the same name must also have the same value.
        - 'drop_conflicts': attrs from all objects are combined, any that have the same name but different values are dropped.

    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",
    ...     attrs={"standard_name": "sea_surface_temperature"},
    ... )
    >>> 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
    Attributes:
        standard_name:  sea_surface_temperature

    >>> 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
    Attributes:
        standard_name:  sea_surface_temperature

    If `x` is a scalar then by default there are no attrs on the result

    >>> xr.where(x < 0.5, 1, 0)