linear fit

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Richard
Richard 2012-1-31
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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采纳的回答

Wayne King
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-.');
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Galina Machavariani
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
Seth DeLand 2022-5-25
Ran in:
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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更多回答（5 个）

Thomas
Thomas 2012-1-31
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
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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Wayne King
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
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Richard
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
vkehayas 2016-9-30
The statistics toolbox is required for
lsline

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Annu Panwar
Annu Panwar 2017-9-13
but anyone has observed that the results are different when you do polyfit by using codes and manually?
  2 个评论
Danhay
Danhay 2018-3-6
that is true. I observed that too
Namira
Namira 2018-8-11
I observed that too. Do you know the solution?

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sabreen haj
sabreen haj 2018-4-27
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
Marcello Wienhoven 2021-1-11
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
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 !

请先登录，再进行评论。

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