1、Matlab圖形處理功能(gngnng)視覺是人們感受世界、認(rèn)識(shí)自然最重要的途徑。數(shù)據(jù)可視化的目的在于：通過圖形，從一堆(y du)雜亂的離散數(shù)據(jù)中觀察數(shù)據(jù)間的內(nèi)在關(guān)系，感受由圖形所傳遞的內(nèi)在本質(zhì)。MATLAB一向注重?cái)?shù)據(jù)的圖形表示，并不斷地采用新技術(shù)改進(jìn)和完備其可視化功能。本文將系統(tǒng)介紹：二維曲線、三維曲線、曲面繪制的基本技法和指令；如何使用線型、色彩、數(shù)據(jù)點(diǎn)標(biāo)記等表現(xiàn)不同數(shù)據(jù)的特征；如何利用著色(zhu s)、燈光照明、烘托表現(xiàn)高維函數(shù)的性狀；如何生成和運(yùn)用標(biāo)識(shí)來注視圖形等。以及利用圖形句柄對(duì)基本圖形對(duì)象進(jìn)行獨(dú)立操作的底層函數(shù)，以獲得圖形操作的更大靈活性。1二維圖形1.1基本繪圖函數(shù)例1單

2、矢量繪圖y=0 0.6 2.3 5 8.3 11.7 15 17.7 19.4 20;plot(y)%title(簡單繪圖舉例);%xlabel(單元下標(biāo));%ylabel(給定的矢量);%grid例2雙矢量繪圖x=0:0.05:4*pi;y=sin(x);plot(x,y)例3a對(duì)數(shù)坐標(biāo)繪圖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建立簡單的極坐標(biāo)圖形t=0:.01:2*pi;polar(t,sin(2*t).*cos(2*t)1.2多重曲線繪圖例4ax為矢量，y為矩陣時(shí)的單組變量繪圖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為矩陣，y為矢量時(shí)的單組變量繪圖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為同樣大小(dxio)的矩陣時(shí)的單組變量繪圖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多組變量(binling)繪圖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(一組變量(binling)繪圖)subplot(1,2,2),plot(x,y1,x,y3,x,y2),title(多組變量繪圖)例5b雙y軸繪圖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曲線的線型、顏色、標(biāo)記例6選擇不同的線型繪圖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選擇不同的標(biāo)記點(diǎn)繪圖t=0:pi/20:2*pi;y=sin(t);plot(t,y,o)例8設(shè)置繪圖線的線型、顏色、寬度、標(biāo)記點(diǎn)的顏色及大小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畫一個(gè)20邊的多

7、邊形，頂角用小圓圈表示t=0:pi/10:2*pi;plot(exp(i*t),-o)axis(square)2圖形的控制(kngzh)與表現(xiàn)2.1圖形(txng)窗口例10asubplot的應(yīng)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將peaks函數(shù)的等高線圖與偽彩色圖畫在一起x,y,z=peaks;contour(x,y,z,20,k)hold onpcolor(x,y,z)shading interphold off2.2坐標(biāo)軸控制命令例11定義坐標(biāo)軸范圍對(duì)觀察圖形的影響x=0:.01:pi/2;plot(x,tan(x),-ro)%axis(0,pi/2,0,5)例12比較不同的顯示方式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圖形的標(biāo)注例13加注坐標(biāo)標(biāo)識(shí)、圖形標(biāo)題和文本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(正弦函數(shù)圖形,FontName,隸書,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(這是用鼠標(biāo)獲取位置而放置的字符串！)例14在標(biāo)題中指定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(時(shí)間(shjin)mus.),ylabel(幅值)例15在當(dāng)前圖形中添加(tin ji)圖例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(曲線(qxin)1,曲線2,曲線3)3特殊圖形3.1條形圖例16a條形圖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軸),ylabel(y軸),zlabel(z軸)subplot(1,2,2),bar3(y),xlabel(x軸),ylabel(y軸),zlabel(z軸)例1

13、6有兩組生物醫(yī)學(xué)的實(shí)驗(yàn)數(shù)據(jù)，一組表示物質(zhì)成分（TCE），一組表示溫度（temp），數(shù)據(jù)是在35天中每隔5天的采樣，將物質(zhì)成分和溫度與時(shí)間的關(guān)系畫在一張圖中。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餅圖例17不分離(fnl)的餅圖x=5.5 74.7 44.5 33.2 46.6;pie(x)例18帶分離(fnl)切塊的餅圖pie(x,0 0 0 0 1)例19a不完整(wnzhng)的餅圖a=0.2 0.3 0.4;pie(a)例19b三維餅圖pie3(1 2 3 4

15、 5,0 1 0 1 0)3.3其他圖形例20直角坐標(biāo)系下矢量的直方圖yn=randn(10000,1);subplot(1,2,1),hist(yn)subplot(1,2,2),hist(yn,20)例21直角坐標(biāo)系下的三維數(shù)組的直方圖y3n=randn(10000,3);hist(y3n)例22二維桿狀圖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用三維桿狀圖表現(xiàn)復(fù)平面快速傅立葉變換計(jì)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(實(shí)部),ylabel(虛部),zlabel(幅值),title(頻率響應(yīng)幅值)例24用三維桿狀圖與其他圖形的疊加表現(xiàn)拉普拉斯變換基函數(shù)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(實(shí)部),ylabel(虛部),zlabel(幅值)例25階梯圖的表現(xiàn)(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=函數(shù)(hnsh)e-(alpha*t)sinbeta*t的階梯圖;text(0.5,-0.2,label,FontSize,14)xlabel(t=0:10,FontSize,14)axis(0 10 -1.2 1.2)例26給定數(shù)據(jù)t=0:pi/10:2*pi;y=sin(t)，觀察在不同(b tn)輸入?yún)?shù)時(shí)scatter函數(shù)的繪圖結(jié)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)4三維圖形例6-27當(dāng)x、y和z都是一維數(shù)組時(shí)的三維線圖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當(dāng)x、y和z都是矩陣時(shí)的三維線圖X,Y=meshgrid(-2:0.1:2);Z=X.*exp(-X.2-Y.2);plot3(X,Y,Z)grid on例29規(guī)定線型、顏色及標(biāo)記點(diǎn)的三維曲線圖t=0:pi/20:5*pi;plot3(sin(t),cos(t),t,:*r)4.3網(wǎng)絡(luò)圖例30繪制網(wǎng)絡(luò)圖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著色表面圖例31a用surf函數(shù)畫一個(gè)橢圓表面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表面色彩渲染函數(shù)(hnsh)shading的應(yīng)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產(chǎn)生一個(gè)(y )旋轉(zhuǎn)柱面圖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觀察透明處理后網(wǎng)格(wn )的變化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函數(shù)的四維表現(xiàn)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圖形處理的高級(jí)技術(shù)5.1視圖例35比較不同視圖的視覺效果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光照和材料反射系數(shù)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顯示效果增強(qiáng)(zngqing)后的二元函數(shù)表面圖及光照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繪制雙光照(gungzho)效果的球sphere(36)axis equallight(Position,1 3 2);light(Position,-3 -1 3);material shinyaxis off例39圖像(t xin)操作x,map=imread(water_lily.jpg);image(x);colormap(map)axis image off例40句柄圖形t=-pi:pi/20:pi;y=sin(t);subplot(2,2,1),plot(t,y)subplot(2,2,