MATLAB Answers

Tom
3

How do I combine multiple plots in one graph?

Asked by Tom
on 10 Dec 2011
Latest activity Commented on by Ina Panci on 10 May 2019
Hi, is there somewhere I can see some examples of scripts that result in multiple plots on one graph?
I know the 'hold' function is part of how to do it, but I'm very new to Matlab and I really need to see some full examples.
If someone could point me towards some that'd be great.

  2 Comments

snr=0:1:15;
for ii=1:length(snr)
x=randint(1,100000); % Generating bits
y=pskmod(x,2); % Generating BPSK modulated data
ynoisy=awgn(y,snr(ii)); % Adding AWGN noise to data
z=pskdemod(ynoisy,2); % Demodulating
error(ii)=length(find(x-z~=0));
end
semilogy(snr,error)
hold
snr=0:1:15;
for ii=1:length(snr)
x=randint(1,100000); % Generating bits
y=pskmod(x,4); % Generating QPSK modulated data
ynoisy=awgn(y,snr(ii)); % Adding AWGN noise to data
z=pskdemod(ynoisy,4); % Demodulating
error(ii)=length(find(x-z~=0));
end
semilogy(snr,error)
grid
You can use this code, but to have multiple plots, you need the subplot which is used as follows:
% Code used in my paper on design of composite riser
% Create a vertical bar chart using the bar function
figure
subplot(2,3,1) % add fourth plot in 2 x 3 grid
bar(1:18, [FibreControl' FibreAxial'], 1)
% Add title and axis labels
title('(a)')
xlabel('Composite Riser Layers')
ylabel('Stress in Fibre Direction (MPa)')
% Add a legend
legend('[1.58:1.62:1.86]', '[1.84:1.62:1.86]')
% Set the axis limits
set(gca, 'XTick', 1:18)
set(gca, 'XLim', [0,19])
set(gca, 'Fontsize', 8)
subplot(2,3,2) % add first plot in 2 x 3 grid
bar(1:18, [FibreControl' FibreAngled'], 1)
% Add title and axis labels
title('(b)')
xlabel('Composite Riser Layers')
ylabel('Stress in Fibre Direction (MPa)')
% Add a legend
legend('[1.58:1.62:1.86]', '[1.58:1.88:1.86]')
% Set the axis limits
set(gca, 'XTick', 1:18)
set(gca, 'XLim', [0,19])
set(gca, 'fontname','arial','fontsize',8,'linewidth',1)
subplot(2,3,3) % add second plot in 2 x 3 grid
bar(1:18, [FibreControl' FibreHoop'], 1)
% Add title and axis labels
title('(c)')
xlabel('Composite Riser Layers')
ylabel('Stress in Fibre Direction (MPa)')
% Add a legend
legend('[1.58:1.62:1.86]', '[1.58:1.62:1.60]')
% Set the axis limits
set(gca, 'XTick', 1:18)
set(gca, 'XLim', [0,19])
set(gca, 'Fontsize', 8)

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6 Answers

Answer by Chandra Kurniawan on 10 Dec 2011
Edited by MathWorks Support Team on 9 Nov 2018
 Accepted Answer

To combine multiple plots in one graph, use the “hold on” command, such as:
plot(1:10)
hold on
plot(11:20)
hold off
For more information, see:

  2 Comments

The alternative to "hold on" that would be applicable to this example is
plot(t,x,'r',t,y,'b')
Hello, what other letters can we use if we have more than two functions to plot?

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Answer by N Narayan rao on 25 Sep 2016
Edited by Walter Roberson
on 15 Jul 2017

x = -3:0.1:3;
y1 = sin(x);
y2 = cos(x);
y3= tan(x);
y4=1./cos(x);
figure
subplot(2,2,1)
plot(x,y1)
title('Subplot 1')
subplot(2,2,2)
plot(x,y2)
title('Subplot 2')
subplot(2,2,3)
plot(x,y3)
title('Subplot 3')
subplot(2,2,4)
plot(x,y4)
title('Subplot 4')

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Answer by Tom
on 10 Dec 2011

Thanks, that's perfect.

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Answer by Raghuram
on 27 Mar 2014

Could you please tell me the same with scatter plot command? That is, to plot multiple scatter plots in one figure?

  3 Comments

x=rand(2,10);
scatter(x(1,:),x(2,:),'r');
hold on
x=rand(2,10);
scatter(x(1,:),x(2,:),'g');
hold on
x=rand(2,10);
scatter(x(1,:),x(2,:),'b');
hold on
x=rand(2,10);
scatter(x(1,:),x(2,:),'c');
You can plot multiple plot just use "hold on" command
can I get best fit line from this method?
"can I get best fit line from this method?"
Best fit lines tend to imply an ordering to the data, but scatter plots tend to imply the data might not be ordered in a way that is compatible with fitting.
But yes, if you have polynomial coefficients for your fit, such as coefficients generated using polyfit(), then you can use polyval() to interpolate values, and you can "hold on" and plot() the values.

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Answer by Cortney Marschner on 8 Oct 2016
Edited by Walter Roberson
on 15 Jul 2017

How do I plot multiple graphs on the same graph using this code?:
hold off
[x, y] = meshgrid(0:0.2:10, 0:0.2:6);
X = x(1,1:51);
dx = ones(size(x));
dy = x;
quiver(x, y, dx, dy)
axis tight
hold on
plot(X, 1+X.^2/2)

  1 Comment

That code already plots multiple lines on the same plot. However, the y range of the second one is much larger than the y range of the first, so the second one takes up most of the space.

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Answer by utkarsh singhvi on 17 Apr 2018

command to plot multiple function on one graph

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