记录一下之前没有遇到过的问题。
1、首先key是一个numpy数组，但是这个赋值给key_new之后改变key_new 同样也会改变key。相当于是他们两个变量指向了同一块地址，所有改变一个另一个就会变。
key
Out[35]:
array([[ 1, 2, 3, 4],
[14, 6, 14, 14],
[13, 2, 1, 9],
[ 9, 12, 12, 6],
[14, 4, 4, 10]])
key_new = key
key_new[0][0]=3
key
Out[37]:
array([[ 3, 2, 3, 4],
[14, 6, 14, 14],
[13, 2, 1, 9],
[ 9, 12, 12, 6],
[14, 4, 4, 10]])
2、不仅仅是numpy的数组，一般的list也是一样。
key1=key.tolist() key2=key1 key1 Out[43]: [[1, 2, 3, 4], [14, 6, 14, 14], [13, 2, 1, 9], [9, 12, 12, 6], [14, 4, 4, 10]] key2 Out[44]: [[1, 2, 3, 4], [14, 6, 14, 14], [13, 2, 1, 9], [9, 12, 12, 6], [14, 4, 4, 10]] key1[0][0]=3 key1 Out[46]: [[3, 2, 3, 4], [14, 6, 14, 14], [13, 2, 1, 9], [9, 12, 12, 6], [14, 4, 4, 10]] key2 Out[47]: [[3, 2, 3, 4], [14, 6, 14, 14], [13, 2, 1, 9], [9, 12, 12, 6], [14, 4, 4, 10]]
3、遇到python里面的数组，记得用copy()函数复制值
key2=key1.copy() key1 Out[56]: [2, 2, 3, 4] key2 Out[57]: [2, 2, 3, 4] key1[0]=1 key1 Out[59]: [1, 2, 3, 4] key2 Out[60]: [2, 2, 3, 4]
