Add background color for some values in a plot of two two variables

Hi everyone. I have two variables av1 and av2. Each variables have 114 data points. I want to draw it in same figure but at same time and point I also want to calculate p value from ttest between av1 and av2. So if the significance difference is less then 0.05 at that data point it should draw a background colour. I attached the figure.

[Ben]

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Answer 1

[Ben]

You can plot a bar graph and then set the FaceAlpha to less than 1.

x = [0 1 2 2 3 4 4 6 7 7];
y = [1 2 2 3 4.5 4.5 6 7];
p = [2.15e-12 2.72e-11 2.397e-10 0.0600 5.613e-09 1.803e-08 4.831e-08...
    8.945e-08 1.874e-07 2.894e-07];
plot(x,'b')
hold on;
plot(y, 'k')
ax = gca;           %Get axis size info
ylimVals = ax.YLim; %Y limits
scaleFact = max(ylimVals);
b1 = bar(scaleFact*(p < 0.05),'b');   %plot blue bar graph
b1.FaceAlpha = 0.5;  %Set transparency to 50%
b1.EdgeAlpha = 0;    %Maybe you want no outline on the bar
ylim(ylimVals); %Set ylim correctly
uistack(b1, 'bottom')   %Move background below other elements

[Muhammad Usman]

@Ben Thank you. These are the two files. Each file contain 114 data points. Actually i give you that figure as example. I want to plot these two data in one figure. Then ttest will be applied on both data, so when the p value will be less then 0.05, at that point in same figure the background color will be appear same as above figure.

[Ben]

Maybe you could show your code for calculating the values? I don't have any experience with ttest, so maybe you could also share a logical index showing at which of the 114 samples you want the background, if you don't want to share the code that makes the data.

[Muhammad Usman]

@Ben Ok I also uploaded the file which contain p values on 114 points. So just need to draw back ground colour on the data point where p<0.05.

x = af; % first data file

y = bf; % second data file

plot(x, 'b')

hold on

plot(y,'k')

hold on

for i = 1:length(x)

if p(i) < 0.05

% i need to do something here to draw background color on data point when p<0.05.

end

end

[Ben]

I've edited my answer and tested the code locally with your data and think it does what you want.

I think the key understanding here is that you don't need to loop through p. MATLAB allows vector calculations, so you can check every cell in p at once.

out = p < 0.05;

Out will be a logical index (that is, 1 where p < 0.05, 0 otherwise) with the same length as p. You can then plot the logical index with a scaling factor to get the background at a consistent height.

[Ben]

@Muhammad Usman Please mark the question as answered if it has been answered.