图形处理与显示功能整理(共9页)

1、Matlab图形处理功能(gngnng)视觉是人们感受世界、认识自然最重要的途径。数据可视化的目的在于：通过图形，从一堆(y du)杂乱的离散数据中观察数据间的内在关系，感受由图形所传递的内在本质。MATLAB一向注重数据的图形表示，并不断地采用新技术改进和完备其可视化功能。本文将系统介绍：二维曲线、三维曲线、曲面绘制的基本技法和指令；如何使用线型、色彩、数据点标记等表现不同数据的特征；如何利用着色(zhu s)、灯光照明、烘托表现高维函数的性状；如何生成和运用标识来注视图形等。以及利用图形句柄对基本图形对象进行独立操作的底层函数，以获得图形操作的更大灵活性。1二维图形1.1基本绘图函数例1单

2、矢量绘图y=0 0.6 2.3 5 8.3 11.7 15 17.7 19.4 20;plot(y)%title(简单绘图举例);%xlabel(单元下标);%ylabel(给定的矢量);%grid例2双矢量绘图x=0:0.05:4*pi;y=sin(x);plot(x,y)例3a对数坐标绘图y=0 0.6 2.3 5 8.3 11.7 15 17.7 19.4 20;subplot(2,2,1),plot(y),title(plot(y);subplot(2,2,2),semilogx(y),title(semilogx(y);subplot(2,2,3),semilogy(y),title

3、(semilogy(y);subplot(2,2,4),loglog(y),title(loglog(y);例3b建立简单的极坐标图形t=0:.01:2*pi;polar(t,sin(2*t).*cos(2*t)1.2多重曲线绘图例4ax为矢量，y为矩阵时的单组变量绘图x=0:pi/50:2*pi;y(1,:)=sin(x);y(2,:)=0.6*sin(x);y(3,:)=0.3*sin(x);plot(x,y)例4bx为矩阵，y为矢量时的单组变量绘图x(1,:)=0:pi/50:2*pi;x(2,:)=pi/4:pi/50:2*pi+pi/4;x(3,:)=pi/2:pi/50:2*pi+

4、pi/2;y=sin(x(1,:);plot(x,y)例4cx和y为同样大小(dxio)的矩阵时的单组变量绘图x(:,1)=0:pi/50:2*pi;x(:,2)=pi/4:pi/50:2*pi+pi/4;x(:,3)=pi/2:pi/50:2*pi+pi/2;y(:,1)=sin(x(:,1);y(:,2)=0.6*sin(x(:,1);y(:,3)=0.3*sin(x(:,1);subplot(1,2,1),plot(x,y)subplot(1,2,2),plot(x,y)例5a多组变量(binling)绘图x=0:pi/50:2*pi;y=sin(x);0.6*sin(x);0.3*si

5、n(x);y1=sin(x);y2=0.6*sin(x);y3=0.3*sin(x);subplot(1,2,1),plot(x,y),title(一组变量(binling)绘图)subplot(1,2,2),plot(x,y1,x,y3,x,y2),title(多组变量绘图)例5b双y轴绘图x=0:0.3:12;y=exp(-0.3*x).*sin(x)+0.5;plotyy(x,y,x,y,plot,stem)t=0:900;A=1000;a=0.005;b=0.005;z1=A*exp(-a*t);z2=sin(b*t);plotyy(t,z1,t,z2,semilogy,plot);1

6、.3曲线的线型、颜色、标记例6选择不同的线型绘图t=0:pi/100:2*pi;y=sin(t);y2=sin(t-0.25);y3=sin(t-0.5);plot(t,y,r-,t,y2,g-,t,y3,b:)例7选择不同的标记点绘图t=0:pi/20:2*pi;y=sin(t);plot(t,y,o)例8设置绘图线的线型、颜色、宽度、标记点的颜色及大小t=0:pi/20:2*pi;y=sin(4*t).*sin(t)/2;plot(t,y,-bs,LineWidth,2,MarkerEdgeColor,k,MarkerFaceColor,y,MarkerSize,10)例9画一个20边的多

7、边形，顶角用小圆圈表示t=0:pi/10:2*pi;plot(exp(i*t),-o)axis(square)2图形的控制(kngzh)与表现2.1图形(txng)窗口例10asubplot的应用(yngyng)t=0:pi/20:2*pi;x,y=meshgrid(t);subplot(2,2,1),plot(sin(t),cos(t),axis equalsubplot(2,2,2),z=sin(x)+cos(y);plot(t,z),axis(0 2*pi -2 2)subplot(2,2,3),z=sin(x).*cos(y);plot(t,z),axis(0 2*pi -1 1)su

8、bplot(2,2,4),z=sin(x).2-cos(y).2;plot(t,z),axis(0 2*pi -1 1)例10b将peaks函数的等高线图与伪彩色图画在一起x,y,z=peaks;contour(x,y,z,20,k)hold onpcolor(x,y,z)shading interphold off2.2坐标轴控制命令例11定义坐标轴范围对观察图形的影响x=0:.01:pi/2;plot(x,tan(x),-ro)%axis(0,pi/2,0,5)例12比较不同的显示方式t=0:pi/20:2*pi;subplot(2,2,1),plot(sin(t),2*cos(t),gr

9、id onsubplot(2,2,2),plot(sin(t),2*cos(t),axis square,grid onsubplot(2,2,3),plot(sin(t),2*cos(t),axis equal,grid onsubplot(2,2,4),plot(sin(t),2*cos(t),axis tight,grid on2.3图形的标注例13加注坐标标识、图形标题和文本t=0:pi/100:2*pi;y=sin(t);plot(t,y),axis(0 2*pi -1 1)xlabel(0leqittrmleqpi,FontSize,16)ylabel(sin(t),FontSiz

10、e,20)title(正弦函数图形,FontName,隶书,FontSize,20)text(3*pi/4,sin(3*pi/4),leftarrowsin(t)=0.707,FontSize,16)text(pi,sin(pi),leftarrowsin(t)=0,FontSize,16)text(5*pi/4,sin(5*pi/4),sin(t)=-0.707rightarrow,FontSize,16,HorizontalAlignment,right)gtext(这是用鼠标获取位置而放置的字符串！)例14在标题中指定TeX字符t=0:pi/100:2*pi;alpha=-0.8;bet

11、a=15;y=sin(beta*t).*exp(alpha*t);plot(t,y)title(itAe-alphaittsinbetaittalphabeta)xlabel(时间(shjin)mus.),ylabel(幅值)例15在当前图形中添加(tin ji)图例x=0:pi/10:2*pi;y1=sin(x);y2=0.6*sin(x);y3=0.3*sin(x);plot(x,y1,x,y2,-o,x,y3,-*)legend(曲线(qxin)1,曲线2,曲线3)3特殊图形3.1条形图例16a条形图y1=4 2 6 8 1 5;bar(y1)y=9 8 6;2 5 8;6 2 9;5

12、8 7;9 4 2;subplot(2,2,1),bar(y)subplot(2,2,2),barh(y)subplot(2,2,3),bar(y,stack)subplot(2,2,4),barh(y,stack)x=1 2 4 7 10;bar(x,y)bar(x,y,stack)x2=0:pi/10:2*pi;y2=sin(x2);bar(x2,y2,r)subplot(1,2,1),bar3(y,group),xlabel(x轴),ylabel(y轴),zlabel(z轴)subplot(1,2,2),bar3(y),xlabel(x轴),ylabel(y轴),zlabel(z轴)例1

13、6有两组生物医学的实验数据，一组表示物质成分（TCE），一组表示温度（temp），数据是在35天中每隔5天的采样，将物质成分和温度与时间的关系画在一张图中。TCE=515 420 370 250 135 120 60 20;temp=29 23 27 25 20 23 23 27;days=0:5:35;bar(days,temp,c)xlabel(Day)ylabel(Temperature(oC)h1=gca;h2=axes(Position,get(h1,Position);plot(days,TCE,LineWidth,3)set(h2,YAxisLocation,right,Colo

14、r,none,XTickLabel,XLim,get(h1,XLim),Layer,top)text(11,380,Concentration,Rotation,-55,FontSize,16)ylabel(TCE Concentration(PPM)title(Bioremediation,FontSize,16)3.2饼图例17不分离(fnl)的饼图x=5.5 74.7 44.5 33.2 46.6;pie(x)例18带分离(fnl)切块的饼图pie(x,0 0 0 0 1)例19a不完整(wnzhng)的饼图a=0.2 0.3 0.4;pie(a)例19b三维饼图pie3(1 2 3 4

15、 5,0 1 0 1 0)3.3其他图形例20直角坐标系下矢量的直方图yn=randn(10000,1);subplot(1,2,1),hist(yn)subplot(1,2,2),hist(yn,20)例21直角坐标系下的三维数组的直方图y3n=randn(10000,3);hist(y3n)例22二维杆状图x=0:0.2:10;y=exp(-0.3*x).*sin(x);subplot(1,2,1),stem(x,y)subplot(1,2,2),stem(x,y,:sr,fill)例23用三维杆状图表现复平面快速傅立叶变换计算th=(0:127)/128*2*pi;x=cos(th);y

16、=sin(th);f=abs(fft(ones(10,1),128);stem3(x,y,f,d,fill)xlabel(实部),ylabel(虚部),zlabel(幅值),title(频率响应幅值)例24用三维杆状图与其他图形的叠加表现拉普拉斯变换基函数t=0:0.1:10;s=0.1+i;y=exp(-s*t);stem3(real(y),imag(y),t,m)hold onhline=plot3(real(y),imag(y),t,k);hold offset(hline,LineWidth,3)xlabel(实部),ylabel(虚部),zlabel(幅值)例25阶梯图的表现(bio

17、xin)方法alpha=0.01;beta=0.5;t=0:10;f=exp(-alpha*t).*sin(beta*t);stairs(t,f)hold onplot(t,f,:*r)hold offlabel=函数(hnsh)e-(alpha*t)sinbeta*t的阶梯图;text(0.5,-0.2,label,FontSize,14)xlabel(t=0:10,FontSize,14)axis(0 10 -1.2 1.2)例26给定数据t=0:pi/10:2*pi;y=sin(t)，观察在不同(b tn)输入参数时scatter函数的绘图结果t=0:pi/10:2*pi;y=sin(t

18、);subplot(3,2,1),scatter(t,y)subplot(3,2,2),scatter(t,y,v)subplot(3,2,3),scatter(t,y,(abs(y)+2).4,filled)subplot(3,2,4),scatter(t,y,30,y,v,filled)subplot(3,2,5),scatter(t,y,(t+1).3,t,filled)4三维图形例6-27当x、y和z都是一维数组时的三维线图t=0:pi/50:10*pi;x=exp(-t/15).*sin(2*t);y=exp(-t/15).*cos(2*t);z=t;plot3(x,y,t)axis

19、 square;grid on例28当x、y和z都是矩阵时的三维线图X,Y=meshgrid(-2:0.1:2);Z=X.*exp(-X.2-Y.2);plot3(X,Y,Z)grid on例29规定线型、颜色及标记点的三维曲线图t=0:pi/20:5*pi;plot3(sin(t),cos(t),t,:*r)4.3网络图例30绘制网络图subplot(2,2,1),mesh(peaks(20);subplot(2,2,2),meshc(peaks(20);subplot(2,2,3),p=peaks(30);p(20:23,9:15)=NaN*ones(4,7);meshz(p);subpl

20、ot(2,2,4),Waterfall(peaks(30);4.4着色表面图例31a用surf函数画一个椭圆表面x=-1.5:0.3:1.5;y=-1:0.2:1;x,y=meshgrid(x,y);z=sqrt(4-x.2/9-y.2/4);figure(1),surf(x,y,z)figure(2),surfl(x,y,z)figure(3),surf(x,y,z),colormap(hot)figure(4),surf(x,y,z),shading interp例31b表面色彩渲染函数(hnsh)shading的应用subplot(2,2,1),surf(peaks),shading f

21、lat;subplot(2,2,2),surf(peaks),shading faceted;subplot(2,2,3),surf(peaks),shading interp;例32产生一个(y )旋转柱面图t=0:pi/12:3*pi;r=abs(exp(-0.25*t).*sin(t);x,y,z=cylinder(r,30);surfl(x,y,z)colormap(pink)shading interp例33观察透明处理后网格(wn )的变化x,y=meshgrid(-8:.5:8);R=sqrt(x.2+y.2)+eps;z=sin(R)./R;subplot(1,2,1),mes

22、h(z),colormap(0 0 1)subplot(1,2,2),mesh(z),colormap(0 0 1),hidden off例34函数的四维表现x=-2:0.1:2;y=-2:0.25:2;z=-2:0.25:2;X,Y,Z=meshgrid(x,y,z);V=X.*exp(-X.2-Y.2-Z.2);xi=-0.7,0.7;yi=0.5;zi=-0.5;slice(X,Y,Z,V,xi,yi,zi)xlabel(x);ylabel(y);zlabel(z);colorbar(horiz)view(-30 45)5图形处理的高级技术5.1视图例35比较不同视图的视觉效果subpl

23、ot(2,2,1),peaks(50)subplot(2,2,2),peaks(50),view(90,0)subplot(2,2,3),peaks(50),view(30,45)subplot(2,2,4),peaks(50),view(2)例36光照和材料反射系数的示例clft=linspace(0,2*pi,100);r=1-exp(-t/2).*cos(4*t);x,y,z=cylinder(r,60);ii=find(x0&y0);z(ii)=NaN;subplot(1,2,1),surf(x,y,z),colormap(pink),shading interpsubplot(1,2

24、,2),surf(x,y,z),colormap(pink),shading interp,light(position,-3,-1,3,style,local)material(0.5 0.4 0.3 10 0.3)例37显示效果增强(zngqing)后的二元函数表面图及光照x,y=meshgrid(-8:.1:8);r=sqrt(x.2+y.2)+eps;z=2*sin(r)./r;surf(x,y,z)shading interp;daspect(5 5 1)axis tightview(-50,30)light(position,-10 -10 2)例38绘制双光照(gungzho)效果的球sphere(36)axis equallight(Position,1 3 2);light(Position,-3 -1 3);material shinyaxis off例39图像(t xin)操作x,map=imread(water_lily.jpg);image(x);colormap(map)axis image off例40句柄图形t=-pi:pi/20:pi;y=sin(t);subplot(2,2,1),plot(t,y)subplot(2,2,