Reduce this array by applying `func` along some dimension(s).

        Parameters
        ----------
        func : function
            Function which can be called in the form
            `f(x, axis=axis, **kwargs)` to return the result of reducing an
            np.ndarray over an integer valued axis.
        dim : str or sequence of str, optional
            Dimension(s) over which to apply `func`.
        axis : int or sequence of int, optional
            Axis(es) over which to repeatedly apply `func`. Only one of the
            'dim' and 'axis' arguments can be supplied. If neither are
            supplied, then the reduction is calculated over the flattened array
            (by calling `f(x)` without an axis argument).
        keep_attrs : bool, optional
            If True, the variable's attributes (`attrs`) will be copied from
            the original object to the new one.  If False (default), the new
            object will be returned without attributes.
        **kwargs : dict
            Additional keyword arguments passed on to `func`.

        Returns
        -------
        reduced : DataArray
            DataArray with this object's array replaced with an array with
            summarized data and the indicated dimension(s) removed.

def reduce(self, func, dim=None, axis=None, keep_attrs=None, **kwargs):
        """Reduce this array by applying `func` along some dimension(s).

        Parameters
        ----------
        func : function
            Function which can be called in the form
            `f(x, axis=axis, **kwargs)` to return the result of reducing an
            np.ndarray over an integer valued axis.
        dim : str or sequence of str, optional
            Dimension(s) over which to apply `func`.
        axis : int or sequence of int, optional
            Axis(es) over which to repeatedly apply `func`. Only one of the
            'dim' and 'axis' arguments can be supplied. If neither are
            supplied, then the reduction is calculated over the flattened array
            (by calling `f(x)` without an axis argument).
        keep_attrs : bool, optional
            If True, the variable's attributes (`attrs`) will be copied from
            the original object to the new one.  If False (default), the new
            object will be returned without attributes.
        **kwargs : dict
            Additional keyword arguments passed on to `func`.

        Returns
        -------
        reduced : DataArray
            DataArray with this object's array replaced with an array with
            summarized data and the indicated dimension(s) removed.
        """

        var = self.variable.reduce(func, dim, axis, keep_attrs, **kwargs)
        return self._replace_maybe_drop_dims(var)