Matlab-进阶绘图

04进阶绘图

Advanced 2D plots

Logarithm Plots 对数绘图

• x = logspace(-1,1,100) 即x从10^-1 到 10^1 一百个项

• x = linspace(0,4*pi,40) 即 x 从0 到 4pi 40个项

• loglog (x,y) 对两个轴取对数 log 以10为底

• semilogx (x,y) 对x轴取对数

• semilogy (x,y) 对y轴取对数

  x = logspace(-1,1,100);
  y = x.^2;
  subplot(2,2,1);
  plot(x,y);
  title(‘Plot’);
  subplot(2,2,2);
  semilogx(x,y);
  title(‘Semilogx’);
  subplot(2,2,3);
  semilogy(x,y);
  title(‘Semilogy’);
  subplot(2,2,4);
  loglog(x, y);
  title(‘Loglog’);
  set(gca,‘Xgrid’,‘on’);

• plotyy(x,y1,x,y2) x相同，y函数不同的对比,左右两个y轴

  x = 0:0.01:20;
  y1 = 200exp(-0.05x).sin(x);
  y2 = 0.8exp(-0.5*x).sin(10x);
  [AX,H1,H2] = plotyy(x,y1,x,y2);
  set(get(AX(1),‘Ylabel’),‘String’,‘Left Y-axis’)
  set(get(AX(2),‘Ylabel’),‘String’,‘Right Y-axis’)
  title(‘Labeling plotyy’);
  set(H1,‘LineStyle’,’–’); set(H2,‘LineStyle’,’:

  统计图表 柱状图 饼状图 极坐标图 梯状图

• hist (变量,几个柱) 整体分布情况

  y = randn(1,1000);
  subplot(2,1,1);
  hist(y,10);
  title(‘Bins = 10’);
  subplot(2,1,2);
  hist(y,50);
  title(‘Bins = 50’);

• bar bar charts 单自变量的统计图

  • bar(变量,‘stacked’) -->堆高起来的单个变量
  • barh(变量) -->柱高向右的柱状图

  x = [1 2 5 4 8]; y = [x;1:5];
  subplot(1,3,1); bar(x); title(‘A bargraph of vector x’);
  subplot(1,3,2); bar(y); title(‘A bargraph of vector y’);
  subplot(1,3,3); bar3(y); title(‘A 3D bargraph’);

• pie 饼状图

  • pie(变量，[0,0,1]) 对于变量的数组中的每个元素是否分裂开,1true,2false
  • pie3 以3D形式绘图

  a = [10 5 20 30];
  subplot(1,3,1); pie(a);
  subplot(1,3,2); pie(a, [0,0,0,1]);
  subplot(1,3,3); pie3(a, [0,0,0,1]);

• polar 极坐标图

  • polar(theta,r) 参数为theta，极坐标平均分成几份 ,r=f(x) ,r半径为x的函数

  x = linspace(0, 4pi, 40); y = sin(x);
  subplot(1,2,1); stairs(y);
  subplot(1,2,2); stem(y);
  x = 1:100; theta = x/10; r = log10(x);
  subplot(1,4,1); polar(theta,r);
  theta = linspace(0, 2pi); r = cos(4theta);
  subplot(1,4,2); polar(theta, r);
  theta = linspace(0, 2pi, 6); r = ones(1,length(theta));
  subplot(1,4,3); polar(theta,r);
  theta = linspace(0, 2*pi); r = 1-sin(theta);
  subplot(1,4,4); polar(theta , r);

• stairs 梯状图

• stem 线状图

  x = linspace(0, 4*pi, 40); y = sin(x);
  subplot(1,2,1); stairs(y);
  subplot(1,2,2); stem(y);

• boxplot

  load carsmall
  boxplot(MPG, Origin);

• error bar e是bar的长度，统计论的误差值，自相关函数

  x=0:pi/10:pi; y=sin(x);
  e=std(y)*ones(size(x));
  errorbar(x,y,e)

Stop sign Wait sign绘制符号

• fill

• t =(1:2:15)’*pi/8; x = sin(t); y = cos(t);
  fill(x,y,‘r’); axis square off;
  text(0,0,‘STOP’,‘Color’, ‘w’,…
  ‘FontSize’, 80, …
  ‘FontWeight’,‘bold’, …
  ‘HorizontalAlignment’…
  , ‘center’);

  t=(0:4)’*pi/2;x=sin(t);y=cos(t);
  fill(x,y,‘y’,‘LineWidth’,5.0);
  axis square off;
  text(0,0,‘WAIT’,‘color’,‘k’,‘FontSize’,70,‘FontWeight’,‘bold’,…
  ‘HorizontalAlignment’,‘center’)

Color space

• [R G B]

• 0 is minimum 1 is maximum

• 8-bit equivalence: 0 is minimum 255 is maximum

• 16-bit equivalence: 00 is minimum FF is maximum

• 改变颜色 绘制五个国家的的金银铜牌数

  G = [46 38 29 24 13]; S = [29 27 17 26 8];

  B = [29 23 19 32 7]; h = bar(1:5, [G’ S’ B’]);

  title(‘Medal count for top 5 countries in 2012 Olympics’);

  ylabel(‘Number of medals’); xlabel(‘Country’);

  legend(‘Gold’, ‘Silver’, ‘Bronze’)

• 色彩作为另一个维度

• meshgrid() 生成3D网格采样点

• imagesc()根据矩阵中的数值大小转换成响应的颜色

  [x, y] = meshgrid(-3:.2:3,-3:.2:3);
  z = x.^2 + x.*y + y.^2; surf( x, y, z); box on;
  set(gca,‘FontSize’, 16); zlabel(‘z’);
  xlim([-4 4]); xlabel(‘x’); ylim([-4 4]); ylabel(‘y’);

  imagesc(z); axis square; xlabel(‘x’); ylabel(‘y’);

• colorbar;指令 显示2D的图的色彩作为第3D的值

• colormap(预设色图name)

  • 常用name:jet,hsv,hot,coolspring,summer,autumn,winter
  • 不常用name:parula,gray,bone,copper,pink,lines,colorcube,prism

3D plots

• plot3 基本3D画图

  x=0:0.1:3*pi; z1=sin(x); z2=sin(2.*x); z3=sin(3.*x);
  y1=zeros(size(x)); y3=ones(size(x)); y2=y3./2;
  plot3(x,y1,z1,‘r’,x,y2,z2,‘b’,x,y3,z3,‘g’); grid on;
  xlabel(‘x-axis’); ylabel(‘y-axis’); zlabel(‘z-axis’);

  t = 0:pi/50:10*pi;

  plot3(sin(t),cos(t),t)

  grid on; axis square;

  turns = 40*pi;

  t = linspace(0,turns,4000);

  x = cos(t).*(turns-t)./turns;

  y = sin(t).*(turns-t)./turns;

  z = t./turns;

  plot3(x,y,z); grid on;

• meshgrid() 生成3D网格采样点

  • 利用mashgird(x,y)生成一个矩阵 x是一个级数,y是一个级数
  • x = -2:1:2; y = -2:1:2;
  • [X,Y] = meshgrid(x,y)

• surf 实色填充3d网格 mesh仅有网格 画图

  x = -3.5:0.2:3.5; y = -3.5:0.2:3.5;
  [X,Y] = meshgrid(x,y);
  Z = X.*exp(-X.^2-Y.2);
  subplot(1,2,1); mesh(X,Y,Z);
  subplot(1,2,2); surf(X,Y,Z);

• surfc meshc :同时在底部加上等高线画图

• surface

• contour(X,Y,Z) 等高线图

  x = -3.5:0.2:3.5;
  y = -3.5:0.2:3.5;
  [X,Y] = meshgrid(x,y);
  Z = X.*exp(-X.^2-Y.2);
  subplot(2,1,1);
  mesh(X,Y,Z);
  axis square;
  subplot(2,1,2);
  contour(X,Y,Z);
  axis square;

• contourf(Z) 实色填充等高线图 Clabel(C,h) 标记等高线数值

  x = -3.5:0.2:3.5; y = -3.5:0.2:3.5;

  [X,Y] = meshgrid(x,y); Z = X.*exp(-X.^2-Y.2);

  subplot(1,3,1); contour(Z,[-.45:.05:.45]); axis square;

  subplot(1,3,2); [C,h] = contour(Z);

  clabel(C,h); axis square;

  subplot(1,3,3); contourf(Z); axis square;

• light()打光角度

• view(角度,角度)观察角度 球坐标系

  sphere(50); shading flat;
  light(‘Position’,[1 3 2]);
  light(‘Position’,[-3 -1 3]);
  material shiny;
  axis vis3d off;
  set(gcf,‘Color’,[1 1 1]);
  view(-45,20);

load cape 

X=conv2(ones(9,9)/81,cumsum(cumsum(randn(100,100)),2)); 

surf(X,'EdgeColor','none','EdgeLighting','Phong',... 

'FaceColor','interp'); 

colormap(map); caxis([-10,300]); 

grid off; axis off;