如果没有for循环，如何将对象放置在NumPy数组的特定索引处？

Question

在没有for循环的情况下如何执行以下操作？你知道吗

import numpy as np

l = np.array([[1, 3], 1, np.nan, [3, 53, 13], ['225gg2g']], dtype=object)

loc = [1, 2]

for i in loc:
    l[i] = ['wgwg', 23, 'g']

Answer 1

In [424]: l = np.array([[1, 3], 1, np.nan, [3, 53, 13], ['225gg2g']], dtype=object)
In [425]: loc = [1,2]
In [426]: l[loc]
Out[426]: array([1, nan], dtype=object)
In [427]: l[loc] = ['wgwg',23,'g']
                                     -
ValueError                                Traceback (most recent call last)
<ipython-input-427-53c5987a9ac6> in <module>()
  > 1 l[loc] = ['wgwg',23,'g']

ValueError: cannot copy sequence with size 3 to array axis with dimension 2

它试图广播3项列表（转换为数组？）放进一个2个项目的插槽。你知道吗

我们可以将该列表包装到另一个列表中，因此它现在是单个项目列表：

In [428]: l[loc] = [['wgwg',23,'g']]
In [429]: l
Out[429]: 
array([list([1, 3]), list(['wgwg', 23, 'g']), list(['wgwg', 23, 'g']),
   list([3, 53, 13]), list(['225gg2g'])], dtype=object)

就像我们一个接一个地复制它，我们得到：

In [432]: l[loc[0]] = ['wgwg',23,'g']
In [433]: l[loc[1]] = ['wgwg',23,'g']
In [434]: l
Out[434]: 
array([list([1, 3]), list(['wgwg', 23, 'g']), list(['wgwg', 23, 'g']),
       list([3, 53, 13]), list(['225gg2g'])], dtype=object)

解决3=>；2映射问题并非易事。你知道吗

但你为什么要这么做？我觉得很可疑。你知道吗

编辑

我先创建一个0d对象数组：

In [444]: item = np.empty([], object)
In [445]: item.shape
Out[445]: ()
In [446]: item[()] = ['wgwg',23,'g']
In [447]: item
Out[447]: array(['wgwg', 23, 'g'], dtype=object)
In [448]: l[loc] = item
In [449]: l
Out[449]: 
array([list([1, 3]), list(['wgwg', 23, 'g']), list(['wgwg', 23, 'g']),
       list([3, 53, 13]), list(['225gg2g'])], dtype=object)