Easy graphics is one of the most famous feature of matlab.

Axis control

Control figure size

1 2	figure(‘position’,[x0,y0,dx,dy]); figure(fig number);

legend control

legend('leg1','leg2','Location','NorthWest');
% hide the legend box
legend boxoff
% set the color of the legend is done via latex grammar
legend('\color{red}leg1','\color{blue}leg2');
% use RGB color value in legend
legend('\color[rgb]{1,1,0}');

depend on how many lines you plot in a figure;

Legend relative position

figure();
sub(1)=subplot(2,1,1);
plot(x1,y1);
leg(1)=legend('f1');
sub(2)=subplot(2,1,2);
plot(x2,y2);
leg(2)=legend('f2');
% control the relative position of legend in whole figure
leg(1).Position=[x1,y1,dx1,dy1];
leg(2).Position=[x2,y2,dx2,dy2];

Display minor ticks

% show minor tick on x axis
set(gca,'XMinorTick','on');
% show minor tick on y axis
set(gca,'YMinorTick','on');

Linewidth

1	set(gca,'LineWidth',2);

Display Latex symbols

% in xlabel, ylabel and title, you can use latex code directly 
xlabel('\frac{\pi x^2}{\sqrt(y+3)}');
% but for legend, the case is a little different, you should use cell, $$ symbol and 'interpreter'
legend({'$\frac{\pi x^2}{\sqrt(y+3)}$'},'interpreter','latex'));

Use log scale axis[1]

figure()
plot(x,y);
% set the x axis as log scale, same operation for x axis
set(gca, 'YScale', 'log');
% to convert it back to normal axis, you can use linear scale
set(gca, 'YScale','linear');

stem plot[2]

stem(x,y) could plot the discrete signals like grass. Its very convenient to display the amplitude of the signal. eg:

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x=0:0.1:1;
figure();
stem(x,sin(x));

fig operation

A figure plotted with matlab can be saved as a .fig figure file. But .fig file actually contains an structure that has objective characters.

Read data from fig file

h=open('data.fig');
x=h.Children.Children.XData;
y=h.Children.Children.YData;
fig1=figure();
plot(x,y);

If the figure is a plot of many subplots, the process to extract its data is even more complicted.
eg. subplot(2,1,:)

clear all;close all;clc;
subdata=openfig('data_subplot.fig');
x1=subdata.Children(1).Children.XData;
y1=subdata.Children(1).Children.YData;
x2=subdata.Children(2).Children.XData;
y2=subdata.Children(2).Children.YData;
figure()
plot(x1,y1,x2,y2);
title('extracted data from subplot fig file');

If the lines in a subplot are more than one, the basic Children of this figure object shall be more complicated. However, the procedure to extract them shall be the same. eg:

1 2	y21=subdata.Children(2).Children(1).YData; y22=subdata.Children(2).Children(2).YData;

Get fig information

You can check the contents of this fig object via this command: get(fig1)

Save .fig file

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fig0=figure();
plot(x,y);
savefig(fig0,'picture.fig');

plot 2 y axis

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[ax h1 h2] = plotyy(x1,y1, x2,y2);
axes(ax(1)); ylabel('First y-label');
axes(ax(2)); ylabel('Second y-layel');

yyaxis to replace plotyy

fig = figure;
left_color = [.5 .5 0];
right_color = [0 .5 .5];
set(fig,'defaultAxesColorOrder',[left_color; right_color]);
yyaxis left
ax1=plot(x1,y1);
yyaxis right
ax2=plot(x2,y2);
% yyaxis中ylim的设置
ax=get(gca);
ax.YAxis(1).Ylimits=[0,300];
ax.YAxis(2).Ylimits=[0,3];

set the parameters of subplot figures

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% this will the set the color of Y axis
sub(2).YAxis(1).Color=[0,0,1]% blue
sub(2).YAxis(2).Color=[1,0,0]% red

2D plot, pcolor

x=(0:0.1:2);% 1*20
y=(0:0.2:1)';% 5*1
yx=y*x;% 5*20
figure();
pcolor(x,y,yx);
shading flat;% smooth the color edge
xlabel('x');
ylabel('y');
colorbar();
title('pcolor');

2D plot, contourf

figure();
contourf(x,y,yx,'edgecolor','none');
colorbar;
xlabel('x');
ylabel('y');
title('contourf');

During the plot of a 2 D plot, the default setting will cover the tick points on X and Y axis. To display it out, follow the above setting.

1	set(gca,'Layer','top');

Set period function

f_test=@(x)( (x<=1)*0 + (x>1&x<2).*(x+2) + (x>=0)*0 );
x_test=0:0.1:5;
y_test=f_test(x_test);
figure();
plot(x_test,y_test);

Annotation for axis[3]

text(x0,y0,‘text’);
This method aims to add comment to the axis object so that is can be used freely in the subplot. While annotation only fit the the figure object, it does not fit to be used in subplot.

Get figure objects

gca: get current axes object
gcf: get current figure object

Add text annotation in fig[4]

% test colorbar position
clear all;close all;clc;
x=linspace(3,5,200);
y=sin(x);
% text annotation to a specific data point
fig1=figure();
x0=3:0.01:4;
y0=cos(x0);
plot(x0,y0,'-*');
text(x0(50),y0(50),'test','Color','red');
% text annotation to a relative position on figure
figure();
fig1=subplot(2,1,1);
plot(x,sin(2*pi*90*x));
set(gca,'fontsize',15,'linewidth',1.5);
text1=annotation('TextBox',[0.2,0.8,0.05,0.05],'String','(a)','FontSize',15,'Color','blue','EdgeColor','none');
fig2=subplot(2,1,2);
set(gca,'fontsize',15,'linewidth',1.5);
ax2=plot(x,x);
text2=annotation('TextBox',[0.2,0.4,0.05,0.05],'String','(b)','FontSize',15,'Color','red','EdgeColor','none');

set position of subplot and colorbar

You can control the position of every figure via changing the position of the fig objects.

% test colorbar position
clear all;close all;clc;
x=linspace(0,1,100);
y=sin(x);
figure();
fig1=subplot(2,1,1);
plot(x,y);
bar1=colorbar();
% hide the value tick on colorbar
set(bar1,'XTickLabel',[]);
legend('sub1');
fig2=subplot(2,1,2);
plot(x,x);
legend('sub2');
% fig.position=[x0,y0,dx,dy]
fig1.Position=[0,0.5,0.5,0.5];
bar1.Position=[0.5,0.5,0.2,0.5];
fig2.Position=[0.5,0,0.5,0.5];

Remove xtick label

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sub=subplot(3,1,1)
plot(x,y);
set(sub,'XTickLabel',[]);

Custom colormap

% custom my colormap for spectrum display
mymap=zeros(7,3);
mymap(7,:)=[139,000,000];% dark red  
mymap(6,:)=[255,000,000];% red          
mymap(5,:)=[255,127,000];% orange
mymap(4,:)=[255,255,000];% yellow
mymap(3,:)=[000,255,000];% green
% mymap(3,:)=[000,255,255];% cyan 青色
mymap(2,:)=[000,000,255];% blue
mymap(1,:)=[255,255,255];% white      
% normalize the color map RGB values to within [0,1]
mymap=mymap/255;

After this kind of setting, you can use this colormap directly via the command: colormap(mymap). Notice the order the colormap is from up to down in the array. You can even use 2D interpolation to make the colormap more dense.

Appendix: matlab default color names and related RGB values

Black        0  0  0 黑
Blue         0  0  1 蓝
Cyan        0  1  1 青
Green      0  1  0 绿
Magenta  1  0  1 紫红
Red         1  0  0 红
White      1  1  1 白
Yellow     1  1  0 黄

You can set different colormaps with different colorbars in subplot. This operation only fit to the new version > 2015R. In the new version matlab, you can use set(gca, colormap_n) to control the colormap of each subplot. And the colorbar will automaticly change along with it.

Change the colors of x,y Ticks

1	set(gca,'xcolor','red','ycolor','green');

Avoid the Axis Tick label overlap

There is no immediate miracles to solve this problem. You can only solve it by adjust the ylim range manually.

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sub(1).YLim=[y1,y2];
sub(2).YAxis(1).Limits=[z11,z12];
sub(2).YAixs(2).Limits=[z21,z22];

Single axis is sub(1), double axes is sub(2).

Control the color, style and boldness of the lines[5]

figure()
plot(x,y,'--green');
plot(x2,y2,'color',[1,0,0],'LineStyle','--');
``` 
The default color names in matlab. For the other colors, you can call them via specify the related RGB values.
```matlab
% line styles
'-' 	Solid line (default)
'--'	Dashed line
':'	Dotted line
'-.' 	Dash-dot line
% line marker styles
 '+'	Plus sign
'o'	Circle
'*'	Asterisk
'.'	Point
'x'	Cross
'square' or 's'         Square
'diamond' or 'd'      Diamond
'^'	Upward-pointing triangle
'v'     Downward-pointing triangle
'>'	Right-pointing triangle
'<'	Left-pointing triangle
'pentagram' or 'p'     Five-pointed star (pentagram)
'hexagram' or 'h'      Six-pointed star (hexagram)

Control the marker size and colors

1	plot(f_TAE_eqs,f_exp_eqs,'o blue','MarkerSize',9,'MarkerFaceColor','blue');

Insert array annotation

% add an arrow in figure
hold on
Ar1= annotation('arrow');
Ar1.X=[0.37,0.65];
Ar1.Y=[0.42,0.48];
Ar1.LineWidth=2;
Ar1.LineStyle='--';
Ar1.Color='red';

The above code controls the relative position of the arrow.

Control the length and boldness of the ticks

% change TickLength of current axis, former is minor TickLength, later is major TickLength 
set(gca,'TickLength',[0.03,0.06]);
% change the Tick width of current axis
set(gca,'LineWidth',1.5);

control the figure boarder[6]

% show figure black border
set(gca,'box','on');
% hide figure black border
set(gca,'box','off');

Set colorbar display range

You can set xlim and ylim via caxis([low, high]) manually.

Add transparent block highlight[7][8]

1 2	hold on ha = area([51, 164],[30,30],'FaceColor','red','FaceAlpha',0.1,'Edgecolor','none');

The two parameters in area [x1,x2]，[y1,y2] defines the position of color block, while the FaceColor determines the color type, FaceAlpha defines tranparence, Edgecolor defines boarder color。

Add verticle lines

t2=3.3;
t3=4.8;
hold on
line([t3,t2],[0,100],'Color',c3,'LineStyle','-.','LineWidth',2);

This can be set by the line function, first parameters set x range，second set y range。You can even set the array with plot.

Adjust contour plot colormap range

To get similar color effect. First you need adjust colormap background value. Then you need to adjust the maximum color value.

Set grid on

% test grid line style control
clear all;close all;clc;
x=0:100;
y=sin(0.1*x);
figure('Position',[0,0,600,500]);
plot(x,y);
xlabel('x');
ylabel('y');
title('test grid style');
grid on;
set(gca,'FontSize',15,'Linewidth',1.5);
set(gca,'XMinorTick','on','YMinorTick','on');% control on/off of minor grids
set(gca, 'xminorgrid', 'on','YMinorGrid','on');% control on/off of minor grid lines
set(gca,'MinorGridLineStyle',':');% set minor grid line style
set(gca,'GridLineStyle','--');% set major grid line style
set(gca,'GridAlpha',0.3);% set grid line transparence