How can I find the peak values of a curve?

Question

Ashfaq Ahmed 2022-8-31

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评论： Abderrahim. B 2022-8-31

Hi all!

So I have these curves which have several peaks. Can anyone please tell me how can I detect the peaks and put a value to those points? The attached picture is manually created -

Any feedback from you will be highly appreciated! Thank you!

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Answer 1

Abderrahim. B 2022-8-31

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Hi!

Use findpeaks for each curve. Put findpeaks function in a for loop together with the plot function.

Demo:

randData = randi(10, 10, 5) ;

for ii = 1: length(randData(1,:))

plot(randData(:,ii))

findpeaks(randData(:,ii), "Annotate","peaks")

hold on

end

Hope this helps

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Ashfaq Ahmed 2022-8-31

Thank you! It helps! How can I use the "text" function to show the values?

Abderrahim. B 2022-8-31

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You are welcome.

Try this:

randData = randi(10, 10, 3) ;

for ii = 1: length(randData(1,:))

% plot(randData(:,ii))

[pks,locs] = findpeaks(randData(:,ii), 'Annotate','peaks');

findpeaks(randData(:,ii))

text(locs-0.04,pks+0.4,split(num2str(pks')))

hold on

end

hold off

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Answer 2

Cris LaPierre 2022-8-31

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If you are using a live script, I suggest using the Find Local Extrema task. You can see an introduction to this tool in this recent live stream. It will allow you to interactively find the right settings to identify your peaks. If you prefer to do it programmatically, look into the findpeaks function.

Once you have the indices of the peaks, you can use the text function to label them in your plot.