python 横坐标旋转

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()