def action_mapping(model_output_act, low_bound, high_bound):
    """ mapping action space [-1, 1] of model output 
        to new action space [low_bound, high_bound].

    Args:
        model_output_act: np.array, which value is in [-1, 1]
        low_bound: float, low bound of env action space
        high_bound: float, high bound of env action space

    Returns:
        action: np.array, which value is in [low_bound, high_bound]
    """
    assert high_bound > low_bound
    action = low_bound + (model_output_act - -1.0) * ((high_bound -
        low_bound) / 2.0)
    return action
