用matplotlib库画图

1、用例一

 import matplotlib.pyplot as plt
 import numpy as np
 x=np.linspace(0,10,100)
 y=np.cos(2*np.pi*x)*np.exp(-x)+0.9
 plt.plot(x,y,'k',color='b',label="$08$",linewidth=3)
 plt.axis([0,6,0,1.8])
 ix=(x>0.8)&(x<3)
 plt.fill_between(x,y,0,where=ix,\
                 facecolor='grey',alpha=0.25)
 plt.text(0.5*(0.8+3),0.2,r"$\int_a^b f(x)\mathrm{d}x$",\
          horizontalalignment='center')
 plt.legend()
 plt.show()

　

2、用例二

 import matplotlib.pyplot as plt
 import numpy as np
 x=np.linspace(0,10,100)
 y=np.cos(2*np.pi*x)*np.exp(-x)+0.9
 plt.plot(x,y,'k',color='b',label="$08$",linewidth=3)
 #plt.axis([0,6,0,1.8])
 #ix=(x>0.8)&(x<3)
 #plt.fill_between(x,y,0,where=ix,\
 #                facecolor='grey',alpha=0.25)
 #plt.text(0.5*(0.8+3),0.2,r"$\int_a^b f(x)\mathrm{d}x$",\
         # horizontalalignment='center')
 plt.legend()
 plt.show()