## Find peaks for a given 2D curve.

Version 1.0.3 (32.4 KB) by
The code is very simple and needs only two lines of code.

Updated 21 Jul 2022

Full call:
PeakValues=FindPeaksSimple(x,y,PeakType,Interpolate)
INPUT:
1 x: x-values. Vector with numbers.
2 y: y-values. Vector with numbers.
Optional values:
You may omit all off them or the trailing value.
3 PeakType: -1: only minima
0: minima and maxima (default)
1: only maxima
4 Interpolate: true or 1: parabolic interpolation
false or 0: no interpolation (default)
If the curve is noisy, you might consider to smooth it beforehand,
OUTPUT:
PeakValues: Array with peak x-positions and peak y-values
Empty PeakValues for no peak at all.
Processing time on my PC is:
No interpolation: 40us overhead + 17ns per sample.
Is for 10^6 samples: 17 ms.
With interpolation: 40us overhead + 17ns per sample + 34ns per peak.
Is for 10^6 samples with 3.4*10^5 peaks=28 ms
If you process always in the same manner, you can delete many code lines.
E.g. you want only nearest maxima:
PeakValues=FindPeaksSimpleMaxima(x,y)
PeakIndx = find(diff(sign(diff(y)))<0)+1;
PeakValues=[x(PeakIndx)',y(PeakIndx)'];
Or you want only maxima interpolated:
PeakValues=FindPeaksSimpleMaximaInterpolated(x,y)
PeakIndx = find(diff(sign(diff(y)))<0)+1;
y1=y(PeakIndx-1);%Left of peak
y2=y(PeakIndx);%At peak
y3=y(PeakIndx+1);%Right of peak
PeakPos=(x(2)-x(1))*(y3-y1)./(4*y2-2*y1-2*y3)+x(PeakIndx);
PeakMinMax=y2-(y3-y1).^2./(8*(y1-2*y2+y3));
PeakValues=[PeakPos(:),PeakMinMax(:)];

### Cite As

Peter Seibold (2023). Find peaks for a given 2D curve. (https://www.mathworks.com/matlabcentral/fileexchange/114145-find-peaks-for-a-given-2d-curve), MATLAB Central File Exchange. Retrieved .

##### MATLAB Release Compatibility
Created with R2020a
Compatible with R2016a and later releases
##### Platform Compatibility
Windows macOS Linux

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Version Published Release Notes
1.0.3

Minor speed improvement.
Some changes in demo.

1.0.2

Minor changes in demo.

1.0.1

Corrected description

1.0.0