def get_trail_max(self, rz_array=None):
    """
    Return the position of the blob maximum. Either in pixel or in (R,Z) coordinates if rz_array
    is passed.
    """
    if (rz_array is None):
        return self.xymax

    # Remember xycom[:,1] is the radial (X) index which corresponds to R
    return rz_array[self.xymax[:,0].astype('int'), self.xymax[:,1].astype('int'), :]