Remove peaks below a threshold using findpeaks function

Hi all,

I know this topic has been discussed before to some extent, but I can't seem to figure out a way to do the following.

I am finding peaks in my kernel distribution function which is returned in terms of PDF and X, where PDF vs. X is plotted. To find the peaks I do the following:

 [Peaks, Locs] = findpeaks(PDF) ; %Find Y value of the peaks
 X_peakVal = X(Locs) ; %Find X value of the peaks

However, I would like to reject some values for some peaks that lie below a threshold:

 [Peaks, Locs] = findpeaks(PDF) ; %Find Y value of the peaks
 Peaks(Peaks < 0.01*max(Peaks)) = [] ; %Reject Y value of peaks below this threshold
 X_peakVal = X(Locs) ; %Find X value of the peaks

The above code does not reject the corresponding indices noted as Locs, such as the corresponding X_peakVal (or X values corresponding to the Y peaks) are also rejected.

What is a way to exclude the corresponding X values to the rejected Y?

Thanks in advance for your help,

KMT.

Answer 1

[Image Analyst]

You also need to remove those points from loc

smallPeakIndexes = Peaks < 0.01*max(Peaks);
Peaks(smallPeakIndexes) = [] ; %Reject Y value of peaks below this threshold
Locs(smallPeakIndexes) = [] ; %Reject Y value of peaks below this threshold

[Konstantinos Tsitsilonis]

Thanks!

Answer 2

[Star Strider]

This tweak to your code should work:

X_peakVal = X(Peaks < 0.01*max(Peaks)) ; %Find X value of the peaks

If that worked for ‘Peaks’ it should work for ‘X’ as well, since it creates the same logical index vector.