numpy 变长元素拼接

>>> a=np.random.rand(3)
>>> a
array([0.22704923, 0.195327  , 0.01280859])
>>> b=np.random.rand(5)
>>> b
array([0.91722758, 0.7993601 , 0.4582875 , 0.08062776, 0.46468199])
>>> c=np.random.rand(7)
>>> c
array([0.74587527, 0.12562136, 0.90951282, 0.05054994, 0.06985652,
       0.61971994, 0.45418771])
>>> g=np.array([a,b,c])  # 变长元素拼接
>>> g
array([array([0.22704923, 0.195327  , 0.01280859]),
       array([0.91722758, 0.7993601 , 0.4582875 , 0.08062776, 0.46468199]),
       array([0.74587527, 0.12562136, 0.90951282, 0.05054994, 0.06985652,
       0.61971994, 0.45418771])], dtype=object)