def _x_orientation_rep_dict(x_orientation):
    """Create replacement dict based on x_orientation."""
    if x_orientation.lower() == 'east' or x_orientation.lower() == 'e':
        return {'x': 'e', 'y': 'n'}
    elif x_orientation.lower() == 'north' or x_orientation.lower() == 'n':
        return {'x': 'n', 'y': 'e'}
    else:
        raise ValueError('x_orientation not recognized.')
