#範例5-8：使用另外一組矩陣數據來建立新的矩陣
import numpy as np
#建立一個二維矩陣
a = np.array([[1,2,3,4],[5,6,7,8],[9,10,11,12]])
print('二維矩陣a=\n', a)

#新矩陣b = [a[1,1],a[0,2]]
b = [a[1,1],a[0,2]]
print('b = [a[1,1],a[0,2]]=', b)

#新矩陣c = a[[0,1,2],[0,1,0]] = [a[0,0],a[1,1],a[2,0]] 
c = a[[0,1,2],[0,1,0]]
print('a[0,0],a[1,1],a[2,0]=', a[0,0],a[1,1],a[2,0])
print('c = a[[0,1,2],[0,1,0]] = [a[0,0],a[1,1],a[2,0]] = ', c)