How do I combine multiple plots in one graph?

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Tom
Tom on 10 Dec 2011
Commented: Mebin Cherian on 25 Nov 2020
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.
  3 Comments
Mebin Cherian
Mebin Cherian on 25 Nov 2020
Hey, @tayyaba, I have to plot graphs of various iterations into the same graph, and the labels are written during each iteration. My problem is that the legend gets overwritten each time instead of being appended to the already existing legend. soln?
semilogy(snr,error(i));
Label=append('Error',error(i));
label(Label);
hold on;

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Accepted Answer

Chandra Kurniawan
Chandra Kurniawan on 10 Dec 2011
Edited: MathWorks Support Team on 9 Nov 2018
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:
  3 Comments
Cleat Zeiler
Cleat Zeiler on 15 Oct 2019
This is the list from the help call:
Various line types, plot symbols and colors may be obtained with
plot(X,Y,S) where S is a character string made from one element
from any or all the following 3 columns:
b blue . point - solid
g green o circle : dotted
r red x x-mark -. dashdot
c cyan + plus -- dashed
m magenta * star (none) no line
y yellow s square
k black d diamond
w white v triangle (down)
^ triangle (up)
< triangle (left)
> triangle (right)
p pentagram
h hexagram

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More Answers (7)

N Narayan rao
N Narayan rao on 25 Sep 2016
Edited: 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')


Raghuram
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
Walter Roberson
Walter Roberson on 15 Jul 2017
"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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Cortney Marschner
Cortney Marschner on 8 Oct 2016
Edited: 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
Walter Roberson
Walter Roberson on 15 Jul 2017
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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utkarsh singhvi
utkarsh singhvi on 17 Apr 2018
command to plot multiple function on one graph

Emil Latypov
Emil Latypov on 16 Apr 2020
Edited: Image Analyst on 16 Apr 2020
In chemistry, the pH of an aqueous solution is a measure of its acidity. The pH scale ranges from 0 to 14, inclusive. A solution with a pH of 7 is said to be neutral, a solution with a pH greater than 7 is basic, and a solution with a pH less than 7 is acidic.
I did it, but my prof said it is not professional. How to do it professionally?
%% Chapter 8 Question 19
%% This script cteats the a vector structure mysol with various solutions
%% and their pH-values and adds another field mysol.acidity.
clear
clc
format compact
mysol(3) = struct('name','bleach','pH',12);
mysol(1) = struct('name','juce','pH',5);
mysol(2) = struct('name','milk','pH',7);
acidity = myacidity(mysol);
for i = 1:3
mysol(i).acidity = strcat(acidity(i,:));
end
mysol
mysol.acidity
function acidity = myacidity(mysol)
% This function receives a vector structure with various solutions and
% their pH-values and determines acidity of solutions.
len = length(mysol);
acidity(len,:) = blanks(7);
for i = 1:len
if mysol(i).pH < 7
acidity(i,:) = 'acidic ';
elseif mysol(i).pH > 7
acidity(i,:) = 'basic ';
else
acidity(i,:) = 'neutral';
end
end
end
  2 Comments
Walter Roberson
Walter Roberson on 17 Apr 2020
The line
mysol(i).acidity = strcat(acidity(i,:));
should probably be rewritten in terms of strtrim()

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Sankirna D. Joge
Sankirna D. Joge on 17 Aug 2020
One must use hold on command after every plot,
plot(x1,y1);
hold on
plot(x2,y2);
hold on
plot(x3,y3);
hold off
This will give output as three plots on a same graph.
  1 Comment
Walter Roberson
Walter Roberson on 17 Aug 2020
This is not correct. "hold on" stays in effect until you turn it off (or the axes is cleared or deleted.)

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