03设置坐标轴1

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(-1,1,50)
y1 = 2*x+1
y2 = x**2

plt.figure()
plt.plot(x,y2)
plt.plot(x,y1,color='red',linewidth=1.0,linestyle='--')

#范围
plt.xlim((-1,2))
plt.ylim((-2,3))
#轴含义（标签）
plt.xlabel('X')
plt.ylabel('Y')
#更换下标
new_ticks = np.linspace(-1,2,5)
print(new_ticks)
plt.xticks(new_ticks)
plt.yticks([-2,-1.8,-1,1.22,3],
           ['really bad','bad','normal','good','realy good'])


plt.show()