How do i plot the line of best fit?
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Nathen Eberhardt
on 16 Apr 2020
Commented: Star Strider
on 16 Apr 2020
So in Pressure Experiments.mat, there is (6,32) data set. I need the whole 5th row and the 6th row of this data.So I made a scatter plot of this data with :
%Load experimental data
load('PressureExperiments.mat', 'PData')
disp(PData)
%Seperating data
A = PData(5,:) %petrol pressure data
B = PData(6,:) %Number of escaping hydrocarbons
figure(1)
scatter(A,B)
How do i make a line of best fit for this? and plot the best line on the same figure?
Thanks
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Accepted Answer
Star Strider
on 16 Apr 2020
Try this:
%Load experimental data
load('PressureExperiments.mat', 'PData')
% disp(PData)
%Seperating data
A = PData(5,:); %petrol pressure data
B = PData(6,:); %Number of escaping hydrocarbons
P = polyfit(A, B, 1); % Linear Fit
Bfit = polyval(P, A);
figure(1)
scatter(A,B)
hold on
plot(A, Bfit,'-r')
hold off
grid
If you want statistics on the fit, and you have the Statistics and Machine Learning Toolbox, use the regress or fitlm functions.
.
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Star Strider
on 16 Apr 2020
The easiest way (assuming that the relation holds beyond the region-of-fit, not always a reliable assumption):
B = polyval(P, 10)
producing:
B =
66.3339
In general, it is not advisable to extrapolate that far beyond the region of it, unless (on the basis of other knowledge) you can be reasonably certain that the linear (or any other) relaionship is generally valid. With a mathematical model of this relationship, it would be possible to use linear or nonlinear parameter estimation techniques to devise a relation that would ber more generally applicable.
.
More Answers (1)
the cyclist
on 16 Apr 2020
Use polyfit to find the line of best fit.
Use the plot command to plot that line
Use the hold command so that the new plot does not overwrite the scatter plot.
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