import numpy as np
A = [[1, 2], [3, 5], [6, 7], [8, 10], [12, 16]]
B = np.array(A)
print(A[:][0]) # 二維清單切片，不能直接按列取值
print([a[0] for a in A]) # 二維清單按列取值
print(B[:, 0]) # 二維數組按列取值
# 清單切片
C = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
print(C[2:])
print(C[2:][:5])
print(C[2:][:5][3:])
print(C[2:][:5][3:][:1])
結果：
[1, 2]
[1, 3, 6, 8, 12]
[ 1 3 6 8 12]
[3, 4, 5, 6, 7, 8, 9, 10]
[3, 4, 5, 6, 7]
[6, 7]
[6]