python numpy 提取数组问题

Question

a=[1,2,3,4,5,6]

现要取数组，每三个为一组，取出下面这样：

l1=[1,2,3]

l2=[2,3,4]

l3=[3,4,5]

l4=[4,5,6]

就是这种取法。请问使用numpy怎么实现？

Answer 1

 import numpy as np

 a = np.array([1,2,3,4,5,6])

  def split(a):
      for x in range(0, 4):
          b = a[x:x+3]
          print b

split(a)