1、用在数组时:

arr = [[1,2,3],[4,5,6],[7,8,9]]
arr2 = array(arr)
arr2.flatten()

2、用在矩阵时:

arr = [[1,2,3],[4,5,6],[7,8,9]]
m = mat(arr)
a.flatten()

3、用在列表时:

a = [[1,2,3],[4,5,6],[7,8,9],['abc','def']]
a1 = [y for x in a for y in x]