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?
采纳的回答
Wayne King
2012-2-1
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 个评论
Richard
2012-2-1
Wayne King
2012-2-1
yfit = P(1)*x+P(2)
is the equation.... P(1) is the slope and P(2) is the intercept
Nikolaus Koopmann
2020-6-3
yfit=@(x)P(1)*x+P(2)
is what he means, i think
Galina Machavariani
2021-9-2
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 !
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")
更多回答（5 个）
Thomas
2012-1-31
1 个投票
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 个评论
Galina Machavariani
2021-9-2
After I did linear fit with equation, What should I write in the command window to generate the code?
Wayne King
2012-1-31
Hi, yes, you can use lsline()
x = 1:10;
y1 = x + randn(1,10);
scatter(x,y1,25,'b','*')
hold on;
lsline;
4 个评论
Richard
2012-1-31
Wayne King
2012-1-31
lsline(), not isline. Did you copy and paste my code? I didn't write isline.
Richard
2012-2-1
vkehayas
2016-9-30
The statistics toolbox is required for
lsline
Annu Panwar
2017-9-13
0 个投票
but anyone has observed that the results are different when you do polyfit by using codes and manually?
sabreen haj
2018-4-27
0 个投票
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
Marcello Wienhoven
2021-1-11
0 个投票
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 个评论
Galina Machavariani
2021-9-2
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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