What is the meaning of "width" and "prominences" in findpeaks

Question

Matlaber 2019-2-7

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/443797-what-is-the-meaning-of-width-and-prominences-in-findpeaks

评论： Star Strider 2021-7-12

It said that:

[pks,locs,w,p] = findpeaks(data) additionally returns the widths of the peaks as the vector w and the prominences of the peaks as the vector p.

w is the widths of the peaks as the vector w

I still unable to find out how they calculate the width.

Example link

In the example below:

x = linspace(0,1,1000);
Pos = [1 2 3 5 7 8]/10;
Hgt = [4 4 2 2 2 3];
Wdt = [3 8 4 3 4 6]/100;
for n = 1:length(Pos)
    Gauss(n,:) =  Hgt(n)*exp(-((x - Pos(n))/Wdt(n)).^2);
end
PeakSig = sum(Gauss);

Plot the individual curves and their sum

plot(x,Gauss,'--',x,PeakSig)
grid

findpeaks(PeakSig,x,'MinPeakProminence',2,'Annotate','extents','WidthReference','halfheight')
[pks,locs,w,p]= findpeaks(PeakSig,x,'MinPeakProminence', 2,'Annotate','extents','WidthReference','halfheight')
title('Signal Peak Widths')

w =

0.2352 0.1725

p =

4.8721 3.0028

Is the w is the width (half-height) and p is height as pointed in the plot?

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Answer 1

Star Strider 2019-2-7

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/443797-what-is-the-meaning-of-width-and-prominences-in-findpeaks#answer_360043

Is the w is the width (half-height) and p is height as pointed in the plot?

Your interpretation of ‘p’ is correct. The value of ‘w’ returned depends on how you define 'WidthReference' (link). You can define it to be full width half maximum (FWHM) if you define it as 'halfheight'.

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Duy Tran 2021-7-12

is it possible to get the endpoints (data points) of the widths apart from the distance?

Star Strider 2021-7-12

It would be necessary to know the half-prominence height (‘y’ value that is apparently half the ‘y’ value of the tallest peak) and then use interp1 to calculate at least one of the ‘x’ values, then adding or subtracting the FWHM value to get the second ‘x’ value. (That could be something of a challenge in the examples in this illustration.)

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