linear fit
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When plotting a scatter plot is it possible to add a linear fit to the the graph without having to go into tools-> basic fitting and clicking on linear and show equations?
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Wayne King
le 1 Fév 2012
lsline is in the Statistics Toolbox, if you do not have that product you can use polyfit() to fit a 1st order polynomial.
x = 1:10;
y1 = x + randn(1,10);
scatter(x,y1,25,'b','*')
P = polyfit(x,y1,1);
yfit = P(1)*x+P(2);
hold on;
plot(x,yfit,'r-.');
5 commentaires
Galina Machavariani
le 2 Sep 2021
Thank you for the answer.
And how can I display linear fit equation on the graph?
I mean not "manual" way in the graph editor, , but the code ...
Thank you !
Seth DeLand
le 25 Mai 2022
You would need to create the string of the equation and then place it on the graph with "text". Here is an expanded version of Wayne's example that does this:
x = 1:10;
y1 = x + randn(1,10);
scatter(x,y1,25,'b','*')
P = polyfit(x,y1,1);
yfit = polyval(P,x);
hold on;
plot(x,yfit,'r-.');
eqn = string(" Linear: y = " + P(1)) + "x + " + string(P(2));
text(min(x),max(y1),eqn,"HorizontalAlignment","left","VerticalAlignment","top")
Plus de réponses (5)
Thomas
le 31 Jan 2012
Also you can always do it once manually, generate data set, create the plot, make the linear fit with the equations, then in the Figure window
File>Generate code..
This will create a MATLAB function for everything that you did manually and can use it again and again if you have more data sets.
1 commentaire
Galina Machavariani
le 2 Sep 2021
After I did linear fit with equation, What should I write in the command window to generate the code?
Wayne King
le 31 Jan 2012
Hi, yes, you can use lsline()
x = 1:10;
y1 = x + randn(1,10);
scatter(x,y1,25,'b','*')
hold on;
lsline;
4 commentaires
Annu Panwar
le 13 Sep 2017
but anyone has observed that the results are different when you do polyfit by using codes and manually?
2 commentaires
sabreen haj
le 27 Avr 2018
Can you help me to write script for calibration curve And give me the equation so i can finde the x value then the result shown in a table with everage of 3 x value and std
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Marcello Wienhoven
le 11 Jan 2021
x = 1:10;
y1 = x + randn(1,10);
scatter(x,y1,25,'b','*')
P = polyfit(x,y1,1);
yfit = P(1)*x+P(2);
hold on;
plot(x,yfit,'r-.');
1 commentaire
Galina Machavariani
le 2 Sep 2021
Thank you for the answer.
And how can I display linear fit equation on the graph?
I mean not "manual" way in the graph editor, , but the code ...
Thank you !
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