将NumPy数组附加到NumPy数组 [英] Append a NumPy array to a NumPy array

问题描述

我有一个numpy_array. [ a b c ]之类的.

I have a numpy_array. Something like [ a b c ].

然后我要将其附加到另一个NumPy数组中(就像我们创建列表列表一样).我们如何创建包含NumPy数组的NumPy数组的数组?

And then I want to append it into another NumPy array (just like we create a list of lists). How do we create an array of NumPy arrays containing NumPy arrays?

我尝试做以下事情没有任何运气

I tried to do the following without any luck

>>> M = np.array([])
>>> M
array([], dtype=float64)
>>> M.append(a,axis=0)
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
AttributeError: 'numpy.ndarray' object has no attribute 'append'
>>> a
array([1, 2, 3])

推荐答案

In [1]: import numpy as np

In [2]: a = np.array([[1, 2, 3], [4, 5, 6]])

In [3]: b = np.array([[9, 8, 7], [6, 5, 4]])

In [4]: np.concatenate((a, b))
Out[4]: 
array([[1, 2, 3],
       [4, 5, 6],
       [9, 8, 7],
       [6, 5, 4]])

或者这个:

In [1]: a = np.array([1, 2, 3])

In [2]: b = np.array([4, 5, 6])

In [3]: np.vstack((a, b))
Out[3]: 
array([[1, 2, 3],
       [4, 5, 6]])

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