有关numpy 数组X[:,0]

import numpy as np
x = np.array([[0,1],[2,3],[4,5],[6,7],[8,9]])
print(x[:,0]) # 取所有行的第0个数据
print(x[:,1]) # 取所有行的第1个数据
print(x[0,:]) # 第0维所有值
print(x[1,:]) # 第1维所有值
print(x[0,0]) 
print(x[0,1]) 
# 溢出print(x[0,2]) 
Y = np.array([[0,1,2],[3,4,5],[6,7,8],[9,10,11],[12,13,14],[15,16,17],[18,19,20]])
print (Y[:,0:3]) #Y[:, m:n]，即取所有数据的第m到n-1列数据，含左不含右
print (Y[:,1:3])
print (Y[:,2:3])

九次输出分别为： 

1. [0 2 4 6 8]
2. [1 3 5 7 9]
3. [0 1]
4. [2 3]
5. 0
6. 1
7. [[ 0  1  2]
 [ 3  4  5]
 [ 6  7  8]
 [ 9 10 11]
 [12 13 14]
 [15 16 17]
 [18 19 20]]
8. [[ 1  2]
 [ 4  5]
 [ 7  8]
 [10 11]
 [13 14]
 [16 17]
 [19 20]]
9. [[ 2]
 [ 5]
 [ 8]
 [11]
 [14]
 [17]
 [20]]