步骤：
1.使用平移使数据在原点居中
1.围绕原点旋转数据（顺时针旋转45度=-pi/4弧度）
1.将数据转换回原始中心
使用一些线性代数：

import numpy as np

x = np.tile([1,2,3,4],8)
y = np.repeat([1,2,3,4,5,6,7,8],4)
A = np.vstack((x,y)) # just a quick example

# Rotation matrix as in e.g. https://en.wikipedia.org/wiki/Rotation_matrix
theta = -np.pi / 4
rotate = np.array([
    [np.cos(theta), -np.sin(theta)],
    [np.sin(theta),  np.cos(theta)]
])

# Translation vector is the mean of all xs and ys. 
translate = A.mean(axis=1, keepdims=True)

应用变换：

out = A - translate    # Step 1
out = rotate @ out     # Step 2
out = out + translate  # Step 3