短小精悍算例：Python中快速产生多行多列空值None列表

方法1：利用Numpy

import numpy as np
a=np.zeros([5,3])
a[a==0.0]=None
a=a.tolist()
print(a)

方法2：利用for循环

c=[[None for j in range(3)] for i in range(5)]
print(c)

结果都是如下：5行3列

[[nan, nan, nan],
 [nan, nan, nan],
 [nan, nan, nan],
 [nan, nan, nan],
 [nan, nan, nan]]