Connect points in two added variable plots of linear regressions

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bsriv
bsriv on 18 Apr 2022
Commented: Voss on 18 Apr 2022
Hi, I am plotting two linear regressions using plot added, and I would like to connect corresponding points with a individual lines:
figure;plotAdded(mdlpre,2);hold on; plotAdded(mdlpost,2); (picture attached).
Each blue x has a corresponding red x. How do I connect each pair with individual lines.
Thank you!

Accepted Answer

Voss
Voss on 18 Apr 2022
Use the output from plotAdded, which is the plotted lines. Get the first line's (data line) XData and YData for each model, and use those to make new lines connecting the models' data points:
load carsmall
MPG = MPG(1:10);
Weight = Weight(1:10);
Year = categorical(Model_Year(1:10));
tbl = table(MPG,Weight,Year);
% first model
mdlpre = fitlm(tbl,'MPG ~ Year + Weight^2');
% second model: just modify the data a bit and run fitlm again
tbl.MPG = tbl.MPG+randn(height(tbl),1);
tbl.Weight = tbl.Weight+100;
mdlpost = fitlm(tbl,'MPG ~ Year + Weight^2');
% plotting: capture the line handles so you can
% make the connection lines later
figure;
h1 = plotAdded(mdlpre,2) % store the lines as h1
h1 =
3×1 Line array: Line (data) Line (fit) Line (95% conf. bounds)
hold on;
h2 = plotAdded(mdlpost,2) % store the lines as h2
h2 =
3×1 Line array: Line (data) Line (fit) Line
% make the connection lines:
xdata = [get(h1(1),'XData'); get(h2(1),'XData')];
ydata = [get(h1(1),'YData'); get(h2(1),'YData')];
xdata(end+1,:) = NaN;
ydata(end+1,:) = NaN;
plot(xdata(:),ydata(:),'--g','DisplayName','pre-post connection')

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