np.expand_dims()用法详解

numpy.expand_dims(a, axis)

作用：扩展数组的维度

例：

def load_pose_cords_from_strings(y_str, x_str):
    """
    x_str = '[..., ..., ..., ...]' (str)
    x_cords = [..., ..., ..., ...] (list)
    x_cords_expanded = [[...], [...], [...], [...],....] (ndarray)
    """
    y_cords = json.loads(y_str)  # json.loads()把str转成list
    x_cords = json.loads(x_str)
    # 在最后一个维度扩展一维，即将长度为18的list转成shape为(18，1)的ndarray数组
    y_cords_expanded = np.expand_dims(y_cords, -1)
    x_cords_expanded = np.expand_dims(x_cords, -1)
    return np.concatenate([y_cords_expanded, x_cords_expanded], axis=1)