# How can I find the peak values of a curve?

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Ashfaq Ahmed on 31 Aug 2022
Commented: Abderrahim. B on 31 Aug 2022
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!

Abderrahim. B on 31 Aug 2022
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
Ashfaq Ahmed on 31 Aug 2022
Thank you! It helps! How can I use the "text" function to show the values?
Abderrahim. B on 31 Aug 2022
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

Cris LaPierre on 31 Aug 2022
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.
Ashfaq Ahmed on 31 Aug 2022
Hi Cris! Thank you so much! Will do that!