a=arange(12)

a.reshape(4,3)转换为4*3的二维数组

 b=np.random.randint(1,6,(3,4))

b.reval()变为一维向量

a=np.arange(4)

out:array([0, 1, 2, 3])

a.shape
out: (4,)

b=a[:,np.newaxis]在列上添加一个维度，变成4*1

out:array([[0],
       [1],
       [2],
       [3]])

b=a[np.newaxis,:]

out:array([[0, 1, 2, 3]])在行上添加一个维度，变成1*4

排序功能

a=np.random.randint(1,10,(6,4))

out:array([[3, 8, 2, 1],
       [1, 9, 9, 3],
       [4, 1, 4, 9],
       [5, 6, 7, 7],
       [5, 1, 9, 4],
       [3, 1, 6, 7]])

b=np.sort(a,axis=1)按行进行排序

out:array([[1, 2, 3, 8],
       [1, 3, 9, 9],
       [1, 4, 4, 9],
       [5, 6, 7, 7],
       [1, 4, 5, 9],
       [1, 3, 6, 7]])

b=np.sort(a,axis=0)按列进行排序

out:array([[1, 1, 2, 1],
       [3, 1, 4, 3],
       [3, 1, 6, 4],
       [4, 6, 7, 7],
       [5, 8, 9, 7],
       [5, 9, 9, 9]])