建空列表list,数组array,矩阵matrix

import numpy as np
empty = []#空列表

for i in range(10):
sqr = i**2
empty.append(sqr)

empty
[0, 1, 4, 9, 16]

import numpy as np

>>>np.zeros(3)
array([ 0.,  0.,  0.])

>>>np.zeros(3,dtype=int)
array([0, 0, 0])

>>>np.zeros((3,4))
array([[ 0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.]])

import numpy as np
ar = np.zeros((3,4))
ma = mat(ar)

>>>ma
matrix([[ 0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.],
[ 0.,  0.,  0.,  0.]])