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How to shade/color overlapped area in the graph?

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Nisar Ahmed
Nisar Ahmed on 27 Jul 2021
Commented: Star Strider on 29 Jul 2021
Hi,
I have plotted two graphs and both have different x and y axis as:
xlabels{1} = 'DEN (gm/cm3)';
xlabels{2} = 'NPHI(.frac)';
ylabels{1} = 'Depth(m)';
ylabels{2} = 'Depth(m)';
[ax,hlT,hlS] = plotxx(DEN,Depth,NEU,Depth,xlabels,ylabels);
Now I want to shade/fill (with yellow color) only area where both graphs are overlapping (depth 1917 - 1967) in the attached figure. How I can do it?

Accepted Answer

Star Strider
Star Strider on 28 Jul 2021
I honestly have no desire to download ‘plotxx’ and learn its intricacies, so I used yyaxis instead here.
The same approach should apply with ‘plotxx’, although I did not do that test:
LD = load('data.mat');
DEN = LD.DEN2;
Depth = LD.Depth2;
NEU = LD.NEU2;
Mv = (Depth >= 1917) & (Depth <= 1967); % Logical ‘Mask’ Vector (Change Dates As Necessary)
figure
yyaxis left
plot(Depth, DEN)
Lyl = ylim; % Left ‘yyaxis’ Limits
ylabel('DEN')
yyaxis right
plot(Depth, NEU)
Ryl = ylim; % Right ‘yyaxis’ Limits
ylabel('NEU')
LRB = [Lyl(:) [1;1]] \ Ryl(:); % Linear Scaling Parameters
hold on
DENR = [DEN ones(size(DEN))] * LRB; % Scale ‘DEN’ To ‘yyaxis right’
patch([Depth(Mv); flipud(Depth(Mv))], [NEU(Mv); flipud(DENR(Mv))], [1 1 1]*0.8, 'EdgeColor','none') % Plot Scaled ‘DEN’ & Fill
hold off
xlabel('Depth')
producing:
This was a bit of a challenge, since it required scaling the ‘DEN’ vector to the yyaxis right limits. That is actually straightforward using a simple linear regression (the ‘LRB’ calculation), then applying it (the ‘DENR’ for ‘DEN Right’ calculation), with ‘DEN’ originally plotted with yyaxis left.
This gave me the opportunity to figure out how to do that, so thank you for posing the probllem!
.
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More Answers (1)

Image Analyst
Image Analyst on 27 Jul 2021
The code in the FAQ will need to be modified slightly for your data:
If you can't figure it out, attach your data in a text or mat file.
  1 Comment
Nisar Ahmed
Nisar Ahmed on 28 Jul 2021
Hi,
Thank you for your answer. I have attached my data of above figure (in .mat file). Can you please help to plot it with color (yellow) shade within upper-lower limits 1917 - 1967 on Y axis of this figure. I am using this code to plot figure on two differet axis with fixed limits of NEU and DEN.
figure(2),
xlabels{1} = 'DEN (gm/cm3)';
xlabels{2} = 'NPHI(.frac)';
ylabels{1} = 'Depth(m)';
ylabels{2} = 'Depth(m)';
[ax,hlT,hlS] = plotxx(DEN,Depth,NEU,Depth,xlabels,ylabels);
set(ax(2),'xlim',[-0.15 0.45]);
set(ax(2),'xdir', 'reverse');
set(ax(2),'ylim',[1910 1980]);
set(ax(1),'ylim',[1910 1980]);
set(ax(1),'ydir', 'reverse');
set(ax(1),'xlim',[1.95 2.95]);
set(ax(2),'ydir', 'reverse');

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