linear fit

Question

Richard 2012-1-31

1
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/27600-linear-fit

评论： Seth DeLand 2022-5-25

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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Answer 1

Wayne King 2012-2-1

11
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/27600-linear-fit#answer_35916

在 MATLAB Online 中打开

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-.');

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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 !

Seth DeLand 2022-5-25

在 MATLAB Online 中打开

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")

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Answer 2

Thomas 2012-1-31

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https://ww2.mathworks.cn/matlabcentral/answers/27600-linear-fit#answer_35834

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.

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Galina Machavariani 2021-9-2

After I did linear fit with equation, What should I write in the command window to generate the code?

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Answer 3

Wayne King 2012-1-31

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/27600-linear-fit#answer_35829

在 MATLAB Online 中打开

Hi, yes, you can use lsline()

x = 1:10;
y1 = x + randn(1,10);
scatter(x,y1,25,'b','*')
hold on;
lsline;

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Richard 2012-2-1

>> clear all

>> x = 1:10;

y1 = x + randn(1,10);

scatter(x,y1,25,'b','*')

hold on;

lsline;

Undefined function or variable 'lsline'.

vkehayas 2016-9-30

在 MATLAB Online 中打开

The statistics toolbox is required for

lsline

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Answer 4

Annu Panwar 2017-9-13

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https://ww2.mathworks.cn/matlabcentral/answers/27600-linear-fit#answer_281454

but anyone has observed that the results are different when you do polyfit by using codes and manually?

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Danhay 2018-3-6

that is true. I observed that too

Namira 2018-8-11

I observed that too. Do you know the solution?

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Answer 5

sabreen haj 2018-4-27

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https://ww2.mathworks.cn/matlabcentral/answers/27600-linear-fit#answer_317590

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