Numpy数组和矩阵相互转换

1、ndarray转换成matrix

import numpy as np
from numpy import random,mat

r_arr=random.rand(4,4)
print('r_arr',r_arr)
r_mat=mat(r_arr)
print(r_mat.I)#求逆

r_arr [[ 0.65603592  0.39908438  0.44722351  0.92652759]
[ 0.32357477  0.45384697  0.31687359  0.73861219]
[ 0.3534119   0.12693696  0.15701767  0.9163409 ]
[ 0.36515841  0.87377377  0.44150506  0.4605718 ]]
r_mat [[ 0.65603592  0.39908438  0.44722351  0.92652759]
[ 0.32357477  0.45384697  0.31687359  0.73861219]
[ 0.3534119   0.12693696  0.15701767  0.9163409 ]
[ 0.36515841  0.87377377  0.44150506  0.4605718 ]]
[[  2.20907786 -11.21482242   4.73076477   4.12886716]
[ -1.79239654  -4.48728612   3.52875987   3.78121743]
[  2.86148809  15.82430961 -11.71577803  -7.82425058]
[ -1.09402215   2.23536661   0.78545617  -0.77549894]]

import numpy as np
from numpy import random,mat,eye

r_arr=random.rand(4,4)
print('r_arr',r_arr)
r_mat=mat(r_arr)
print('r_mat',r_mat)
r_invmat=r_mat.I
# print(r_mat.I)
r2_mat=r_mat*r_invmat
print('r2_mat',r2_mat)
print('error',r2_mat-eye(4))