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()
...)
