legend图例

import  numpy
from  matplotlib  import  pyplot
x=numpy.linspace(-3,3,50)
y1=2*x+1
y2=x**2
pyplot.rcParams['font.sans-serif']=['simhei'] #显示中文标签
pyplot.rcParams['axes.unicode_minus']=False



pyplot.figure(num='第一幅图',figsize=(5,5))
k1,=pyplot.plot(x,y2,label='up')
k2,=pyplot.plot(x,y1,color='red',linewidth=1,linestyle='--',label='down')






pyplot.legend(handles=[k1,k2],labels=['抛物线','直线'],loc='best')   #可以显示图例




#设置坐标轴范围
pyplot.xlim((-1,2))
pyplot.ylim((-2,2))

#设置坐标轴标签
pyplot.xlabel('i am x')
pyplot.ylabel('i am y')

#设置坐标轴刻度值
a=numpy.linspace(-1,2,5)
pyplot.xticks(a)
pyplot.yticks([-2,0,2],[r'$really\ bad$',r'$normal$',r'$really\ good$'])
pyplot.show()