matplotlib实例

import matplotlib.pyplot as plt
import numpy as np

x=np.arange(-2*np.pi,2*np.pi,0.01)
y=np.sin(3*x)/x
y2=np.sin(2*x)/x
y3=np.sin(x)/x

plt.plot(x,y,color='b')
plt.plot(x,y2,color='r')
plt.plot(x,y3,color='g')

plt.xticks([-2*np.pi,-np.pi,0,np.pi,2*np.pi],[r'$-2\pi$',r'$-\pi$',r'$0$',r'$+\pi$',r'$+2\pi$'])
plt.yticks([-1,0,+1,+2,+3],[r'$-1$',r'$0$',r'$+1$',r'$+2$',r'$+3$'])

plt.annotate(r'$\lim_{x\to 0}\frac{\sin(x)}{x}1$',xy=[0,1],xycoords='data',xytext=[30,30],fontsize=16,textcoords='offset points',
             arrowprops=dict(arrowstyle='->',connectionstyle='arc3,rad=.2'))


ax=plt.gca()
ax.spines['right'].set_color('none')
ax.spines['top'].set_color('none')
ax.xaxis.set_ticks_position('bottom')
ax.spines['bottom'].set_position(('data',0))
ax.yaxis.set_ticks_position('left')
ax.spines['left'].set_position(('data',0))