![x[:,:,None,:]-x[:,:,:,None]](/uploads/reation/bcimg4.png)
x[:,:,None,:]-x[:,:,:,None]
x[:,:,None,:]-x[:,:,:,None]None相当于在数组中多加一个维度。输入：x = np.arange(24).reshape((2,3,4))输出：array([[[ 0, 1, 2, 3], [ 4, 5, 6, 7], [ 8, 9, 10, 11]], [[12, 13, 14, 15], [16, 17, 18, 19], [20, 21, 22, 23]]]) x
