using a forloop to create vertical lines between regression line and scatter plot

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Elisa Caruana
Elisa Caruana 2022-4-13
评论： Elisa Caruana 2022-4-14
I have these X and Y variables
X=[1;2;3;4;5;6;7;8;9;10];
Y=[17;7;15;13;17;34;35;30;46;31];
I created a scatter plot using
scatter(X,Y,'+','r')
and this is the line of best fit (regression line)
Y =5.9333+3.3758*X;
i need to draw VERTICAL lines from the observed values given in the scatter plot to the fitted line, and measure their distance.
how can I do this using a forloop with MATLAB please? (was specifically asked to use a forloop)

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回答（1 个）

Voss
Voss 2022-4-14
编辑：Voss 2022-4-14
Ran in:
X=[1;2;3;4;5;6;7;8;9;10];
Y=[17;7;15;13;17;34;35;30;46;31];
% I created a scatter plot using
scatter(X,Y,'+','r')
% and this is the line of best fit (regression line)
% Y =5.9333+3.3758*X;
% calculate and plot the fitted line:
mb = polyfit(X,Y,1)
mb = 1×2
3.3758 5.9333
Y_fit = polyval(mb,X);
hold on
plot(X,Y_fit,'--b')
% construct and plot the vertical lines:
% (without for loop)
nans = NaN(numel(X),1);
xdata = [X X nans].';
ydata = [Y Y_fit nans].';
plot(xdata(:),ydata(:),'g');
% calculate the lengths of the vertical line segments:
len = abs(Y-Y_fit)
len = 10×1
7.6909 5.6848 1.0606 6.4364 5.8121 7.8121 5.4364 2.9394 9.6848 8.6909
% (put the scatter plot on top of the others)
set(gca(),'Children',flip(get(gca(),'Children')))
  2 个评论
Star Strider
Star Strider 2022-4-14
This is the complete solution to a homework problem.
Note that the regression equation is provided. It does not have to be calculated.
Voss
Voss 2022-4-14
I wanted to make sure the provided equation was correct.
I'll edit it to remove the loop, thus rendering the solution incomplete.

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