在matlab绘图中，线条较多时导致图例较长回遮挡原图/将图例分类，解决方案将图例分为多个。
一、多个图例一起显示
r = 10;
a = 0;
b = 0;
t=0:0.1:2.1*pi;
x=a+r*cos(t);
y=b+r*sin(t);
plot(x,y,'r','linewidth',4);hold on
axis equal
plot([0 0],[1 10],'b','linewidth',4);
legend('圆形','line')
二、多个图例分开显示
r = 10;
a = 0;
b = 0;
t=0:0.1:2.1*pi;
x=a+r*cos(t);
y=b+r*sin(t);
A1=plot(x,y,'r','linewidth',4);%圆
hold on
axis equal
A2=plot([0 0],[1 10],'b','linewidth',4);%直线
legend([A1],'圆形')
ah=axes('position',get(gca,'position'),...'visible','off');
legend(ah,[A2],'line')
