解决pythonmatplotlib画水平直线的问题

import numpy as np #使用import导入模块numpy&＃xff0c;并简写成np
import matplotlib.pyplot as plt #使用import导入模块matplotlib.pyplot&＃xff0c;并简写成plt
plt.figure(figsize&＃61;(8,4)) #设置绘图对象的宽度和高度t &＃61; np.arange(0,1.1,0.1)
theta &＃61; 30&＃43;15*(t**2)
theta_v &＃61; 30*t
theta_accel &＃61; 30 plt.plot(t,theta,label&＃61;"$theta$",color&＃61;"red",linewidth&＃61;2)
plt.plot(t,theta_v,label&＃61;"$thetaV$",color&＃61;"green",linewidth&＃61;2)
#plt.plot(t,theta_accel,label&＃61;"$thetaAccel$",color&＃61;"blue",linewidth&＃61;2)t &＃61; np.arange(1,3.1,0.1)
theta &＃61; 45&＃43;30*(t-1)
theta_v &＃61; 30
theta_accel &＃61; 0 plt.plot(t,theta,label&＃61;"$theta$",color&＃61;"red",linewidth&＃61;2)
#plt.plot(t,theta_v,label&＃61;"$thetaV$",color&＃61;"green",linewidth&＃61;2)
#plt.plot(t,theta_accel,label&＃61;"$thetaAccel$",color&＃61;"blue",linewidth&＃61;2)t &＃61; np.arange(3,4.1,0.1)
theta &＃61; 120-15*((4-t)**2)
theta_v &＃61; 30*(4-t)
theta_accel &＃61; -30 plt.plot(t,theta,label&＃61;"$theta$",color&＃61;"red",linewidth&＃61;2)
plt.plot(t,theta_v,label&＃61;"$thetaV$",color&＃61;"green",linewidth&＃61;2)
#plt.plot(t,theta_accel,label&＃61;"$thetaAccel$",color&＃61;"blue")plt.ylim(-40,200) #使用plt.ylim设置y坐标轴范围
plt.xlim(-1,5)
plt.xlabel("Time(s)") #用plt.xlabel设置x坐标轴名称
plt.legend(loc&＃61;&＃39;upper left&＃39;) #设置图例位置
plt.grid(True)
plt.show()


#plt.plot(t,theta_accel,label&＃61;"$thetaAccel$",color&＃61;"blue",linewidth&＃61;2)

theta_accel &＃61; -30 &＃43;t*0


"""niku 习题5.5"""
import numpy as np #使用import导入模块numpy&＃xff0c;并简写成np
import matplotlib.pyplot as plt #使用import导入模块matplotlib.pyplot&＃xff0c;并简写成plt
plt.figure(figsize&＃61;(8,4)) #设置绘图对象的宽度和高度t &＃61; np.arange(0,1.1,0.1)
theta &＃61; 30&＃43;15*(t**2)
theta_v &＃61; 30*t
theta_accel &＃61; 30&＃43;t*0 plt.plot(t,theta,label&＃61;"$theta$",color&＃61;"red",linewidth&＃61;2)
plt.plot(t,theta_v,label&＃61;"$thetaV$",color&＃61;"green",linewidth&＃61;2)
plt.plot(t,theta_accel,label&＃61;"$thetaAccel$",color&＃61;"b")t &＃61; np.arange(1,3.1,0.1)
theta &＃61; 45&＃43;30*(t-1)
theta_v &＃61; 30&＃43;t*0
theta_accel &＃61; 0 &＃43;t*0 plt.plot(t,theta,label&＃61;"$theta$",color&＃61;"red",linewidth&＃61;2)
plt.plot(t,theta_v,label&＃61;"$thetaV$",color&＃61;"green",linewidth&＃61;2)
plt.plot(t,theta_accel,label&＃61;"$thetaAccel$",color&＃61;"b",linewidth&＃61;2)t &＃61; np.arange(3,4.1,0.1)
theta &＃61; 120-15*((4-t)**2)
theta_v &＃61; 30*(4-t)
theta_accel &＃61; -30 &＃43;t*0 plt.plot(t,theta,label&＃61;"$theta$",color&＃61;"red",linewidth&＃61;2)
plt.plot(t,theta_v,label&＃61;"$thetaV$",color&＃61;"green",linewidth&＃61;2)
plt.plot(t,theta_accel,label&＃61;"$thetaAccel$",color&＃61;"b")plt.ylim(-40,125) #使用plt.ylim设置y坐标轴范围
plt.xlim(-1,5)
plt.xlabel("Time(s)") #用plt.xlabel设置x坐标轴名称
&＃39;&＃39;&＃39;设置图例位置&＃39;&＃39;&＃39;
#plt.legend(loc&＃61;&＃39;upper right&＃39;) #设置图例位置
plt.grid(True)
plt.show()