python旋转坐标

数据旋转公式 x1=cos(angle)*x-sin(angle)*y; y1=cos(angle)*y+sin(angle)*x;

从数学上来说，此公式可以用来计算某个点绕另外一点旋转一定角度后的坐标，例如：A（x，y）绕B（a，b)旋转β度后的位置为C（c，d），则x，y，a，b，β，c，d有如下关系式：

import matplotlib.pyplot as plt
import numpy as np
import math
a = [0,1,3,3,2,2]
b = [3,4,2,1]
c = [3,3,2,3]

a = np.array(a)
b = np.array(b)
c = np.array(c)

def rotate(angle,valuex,valuey):
    rotatex = math.cos(angle)*valuex -math.sin(angle)*valuey
    rotatey = math.cos(angle)*valuey + math.sin(angle)* valuex
    rotatex = rotatex.tolist()
    rotatey = rotatey.tolist()
    xy = rotatex + rotatey
    return xy
def getLen(x1,y1,x2,y2):
    diff_x = (x1-x2)**2
    diff_y = (y1-y2)**2
    length = np.sqrt(diff_x+diff_y)
    return length

lie = np.linspace(0,2,20) #画图时横纵坐标刻度，影响着它们的形状，可以设置一下刻度分布
for i in lie:
    t = math.pi*i
    a1 = rotate(t,a[0:3],a[3:6])
    b1 = rotate(t,b[0:2],b[2:4])
    c1 = rotate(t,c[0:2],c[2:4])
    len1 = getLen(a[0],a[3],a[1],a[4])
    len2 = getLen(a1[0],a1[3],a1[1],a1[4])
    print(len1)
    print(len2)
    print("旋转后长度是否相等",len1==len2)
    plt.plot(a[0:3],a[3:6],color='green')
    plt.plot(b[0:2],b[2:4],color='green')
    plt.plot(c[0:2],c[2:4],color='green')
    plt.plot(a1[0:3],a1[3:6],color='red')
    plt.plot(b1[0:2],b1[2:4],color='red')
    plt.plot(c1[0:2],c1[2:4],color='red')
    plt.xticks(np.arange(-5,5,0.5))
    plt.yticks(np.arange(-5,5,0.5))
  
    plt.show()