findpeaks ( 'WidthRefe​rence','ha​lfheight' ) not finding width of peak

Hi

I'm trying to find ( 'WidthReference','halfheight') something like this image

but it is not showing using this code , could you please show

me where is my error .

order =3 ;
framelen =13;

Averages=[R,L]';
Averages=mean(Averages)';
AV=smooth(Averages,6);
x=AV;
lx = 20;

sgf = sgolayfilt(x,order,framelen);

plot(sgf);
hold on;

findpeaks(sgf,'MinPeakProminence',0.003);
[pks,locs,widths,proms]=findpeaks(sgf,'Annotate','extents','WidthReference','halfheight');
pks= -pks;

plot(locs,pks,'g*');
text(locs+.02,pks,num2str((1:numel(pks))'));

this the output I get

Answer 1

[Greg Dionne]

I think you wanted this instead:

findpeaks(sgf,'MinPeakProminence',0.003,'WidthReference','halfheight','Annotate','extents');
[pks,locs,widths,proms]=findpeaks(sgf,'MinPeakProminence',0.003,'WidthReference','halfheight');

(use the same settings for when you plot without output arguments vs. when you do your assignment).

[sarmad m]

I did what you suggested to me like this : but again not showing the halfheight or peaks , what is wrong ?

order =9 ;
framelen =13;
x=-AV;
lx = 20;

 sgf = sgolayfilt(x,order,framelen);

 plot(sgf);
 hold on;
 sgf=-sgf;

 findpeaks(sgf,'MinPeakProminence',0.006,'WidthReference','halfheight','Annotate','extents');
[pks,locs,widths,proms]=findpeaks(sgf,'MinPeakProminence',0.006,'WidthReference','halfheight');

 pks = -pks;
plot(locs,pks,'g*');
text(locs+.02,pks,num2str((1:numel(pks))'));

[Greg Dionne]

It's probably not liking the fact that you're using the 'halfheight' flag with a negative baseline. Since your peak values are negative, your reference level needs to be brought up. My guess is you want to add +0.02 to sgf to bring up the baseline. (say "sgf = 0.02-sgf" instead of "sgf = -sgf".

[sarmad m]

thanks it works now

[Netanel shachak]

Hi,

Is there any way to determined spacific width indipendent the peak height?

i have a signal of pump (RPM) - i'm looking for time interval that the the RPM was above a spacific value with a width grater than a spacific value. for example:

i tried using findpeaks:

m=10;

pks=110;

findpeaks(Y,t,'Annotate','extents','MinPeakWidth',minutes(m),'MinPeakHeight',pks);

but in that case it find point with:

pks>110 & width=pks/2;

any suggust?

Answer 2

[sarmad m]

I'm using R2017a version .I tried the example that in the documentation and it shows the halfheight correctly . but when I try it on my data it not showing them

[Amanda Figueroa]

I had the same issue until I removed the outputs (pks, locs, widths,proms)

[pks,locs,widths,proms] = findpeaks(Peaks(:,2),Peaks(:,1),...
    'MinPeakHeight',4e7,'MinPeakProminence',4e6,'Annotate','Extents'...
    );

The plot should show up if you remove them as shown below:

findpeaks(Peaks(:,2),Peaks(:,1),...
    'MinPeakHeight',4e7,'MinPeakProminence',4e6,'Annotate','Extents'...
    );

And this is my plot (zoomed in):

Answer 3

[Matlaber]

Maybe you can paste your code here and have a look.

Are you able to find the peaks on your data?