newaxis顧名思義就是插入新維度的意思，比如原來是一維數劇變成二維數劇，原來是二維變成三維，

python將二維陣列變為三維陣列的舉例如下：

x_data = np.linspace(-1,1,6)
a=x_data.reshape((2,3))
c = a[:,np.newaxis,:]
b = a[np.newaxis,:,:]
d = a[:,:,np.newaxis]

print(a.shape)
print(b.shape)
print(c.shape)
print(d.shape)
print('________________')

輸出結果：

D:\python\python.exe D:/pycharm/workspace/work_3.6.1/test01.py
(2, 3)
(1, 2, 3)
(2, 1, 3)
(2, 3, 1)
________________


Process finished with exit code 0