data.py 文件源码

def get_z(self, var, coords=None):
        """
        Get the vertical (z-) coordinate of a variable

        This method searches for the z-coordinate in the :attr:`ds`. It first
        checks whether there is one dimension that holds an ``'axis'``
        attribute with 'Z', otherwise it looks whether there is an intersection
        between the :attr:`z` attribute and the variables dimensions, otherwise
        it returns the coordinate corresponding to the third last dimension of
        `var` (or the second last or last if var is two or one-dimensional)

        Possible types
        --------------
        var: xarray.Variable
            The variable to get the z-coordinate for
        coords: dict
            Coordinates to use. If None, the coordinates of the dataset in the
            :attr:`ds` attribute are used.

        Returns
        -------
        xarray.Coordinate or None
            The z-coordinate or None if no z coordinate could be found"""
        coords = coords or self.ds.coords
        coord = self.get_variable_by_axis(var, 'z', coords)
        if coord is not None:
            return coord
        zname = self.get_zname(var)
        if zname is not None:
            return coords.get(zname)
        return None