Python | 我预计不会出现的 Plot

Question

The image I thought was this one.

But.. I only get this empty one every time I try.

I don't know why the line is missing.. and what I am missing..

import math
from matplotlib import pyplot as plt
import numpy as np

dx=42; dy=-17; ab=10.5;  bc=42;  cd=24; be=65; ef=5;
ml = np.arange(0, 2*math.pi, math.pi/180)

for theta in ml:
    alpha = -90*math.pi/180
    P=2*cd*(dx-ab+math.cos(theta))
    Q=2*cd*(dy-ab+math.sin(theta))
    R=(dx**2)+(dy**2)+(ab**2)+(cd**2)-(bc**2)-(2*ab+(math.cos(theta))+dy+(math.sin(theta)))

    math_cos_phi=((-P*R)-(Q*math.sqrt((P**2)+(Q**2)-(R**2))))/((P**2)+(Q**2));
    math_sin_phi=((-Q*R)+(P*math.sqrt((P**2)+(Q**2)-(R**2))))/((P**2)+(Q**2));
    a = math_cos_phi;  b = math_sin_phi
    phi=math.atan2(a,b);

    math.cos_psi=((dx+cd+(math_cos_phi))-(ab+math.cos(theta)))/bc;
    math.sin_psi=((dy+cd+(math_sin_phi))-(ab+math.sin(theta)))/bc;
    c = math.cos_psi;  d = math.sin_psi;

    psi=math.atan2(c,d); 
    Fx=ab*math.cos(theta)+be*math.cos(psi)+ef*math.cos(psi+alpha);
    Fy=ab*math.sin(theta)+be*math.sin(psi)+ef*math.sin(psi+alpha);
    plt.plot(Fx,Fy, c = 'g', linewidth=2);
plt.show()

Data=[theta*180/math.pi,Fx,Fy];

Answer 1

Did you mean this? (you have your plot inside the loop for each point. You need to move it to outside of the loop and accumulate all the Fx's and Fy's ):

import math
from matplotlib import pyplot as plt
import numpy as np

dx=42; dy=-17; ab=10.5;  bc=42;  cd=24; be=65; ef=5;
ml = np.arange(0, 2*math.pi, math.pi/180)
Fx, Fy = [], []

for theta in ml:
    alpha = -90*math.pi/180
    P=2*cd*(dx-ab+math.cos(theta))
    Q=2*cd*(dy-ab+math.sin(theta))
    R=(dx**2)+(dy**2)+(ab**2)+(cd**2)-(bc**2)-(2*ab+(math.cos(theta))+dy+(math.sin(theta)))

    math_cos_phi=((-P*R)-(Q*math.sqrt((P**2)+(Q**2)-(R**2))))/((P**2)+(Q**2));
    math_sin_phi=((-Q*R)+(P*math.sqrt((P**2)+(Q**2)-(R**2))))/((P**2)+(Q**2));
    a = math_cos_phi;  b = math_sin_phi
    phi=math.atan2(a,b);

    math.cos_psi=((dx+cd+(math_cos_phi))-(ab+math.cos(theta)))/bc;
    math.sin_psi=((dy+cd+(math_sin_phi))-(ab+math.sin(theta)))/bc;
    c = math.cos_psi;  d = math.sin_psi;

    psi=math.atan2(c,d); 
    Fx.append(ab*math.cos(theta)+be*math.cos(psi)+ef*math.cos(psi+alpha))
    Fy.append(ab*math.sin(theta)+be*math.sin(psi)+ef*math.sin(psi+alpha))
plt.plot(Fx,Fy, c = 'g', linewidth=2);
plt.show()

Data=[theta*180/math.pi,Fx,Fy];

output: