Help with loop script

I have created a loop script to calculate peak amplitude for ECG data

x is the data file

TS is the total number of data points

L is the number of points sampled in each window

I have included an outlier code to remove peaks that are more than 3 std deviations from the mean.

I have written the code so I create a matrix that shows mean peak amplitude, peak std dev, number of peaks after outlier removal and number of peaks before outlier removal for each window.

In my code Bx represents the peaks detected for each window.

After I run my script Bx only shows the peaks detected for the last window

I want to alter my script so I can view Bx for all windows, Ideally in a matrix

Can somebody please help me?

My code is below:

Thanks!

xMatrix=reshape(x,L,TS/L);
%Filtering
[b,a]=butter(4,[0.0390625 0.46875],'bandpass');       %4th order bandpass butterworth 5-60Hz
xMatrix=filtfilt(b,a,xMatrix);

for N=(1:TS/L)
%Findpeaks
figure(1) % filtered ECG Plot x
plot(xMatrix(:,N));
[xpks,locs]=findpeaks(xMatrix(:,N),'MinPeakDistance',20,'MinPeakHeight',750);
Bx=rmoutliers(xpks,'mean');
[Bx,TFx]=rmoutliers(xpks);
xpeakmean=mean(Bx);
xpeakstd=std(Bx);
xspikes=numel(Bx);
xHR=numel(xpks);
findpeaks(xMatrix(:,N),'MinPeakDistance',20,'MinPeakHeight',750);
title('filtered ECG x')
xlabel('Samples')
ylabel('uV')
xlim([0 L])
ylim([-2000 2000])

%New Matrix
xpkMatrix(N,1)=xpeakmean;
xpkMatrix(N,2)=xpeakstd;
xpkMatrix(N,3)=xspikes;
xpkMatrix(N,4)=xHR;
end

[Ridwan Alam]

Hi Sam, did the response below work?

[sam van Bohemen]

Hi Ridwan

I managed to figure it out

Thanks

Answer 1

[Ridwan Alam]

If you can share x, I could test it properly. Otherwise, I think you just need 'hold on':

xMatrix=reshape(x,L,TS/L);
%Filtering
[b,a]=butter(4,[0.0390625 0.46875],'bandpass');       %4th order bandpass butterworth 5-60Hz
xMatrix=filtfilt(b,a,xMatrix);
figure(1) % filtered ECG Plot x
for N=(1:TS/L)
    %Findpeaks
    plot(xMatrix(:,N));hold on;
    [xpks,locs]=findpeaks(xMatrix(:,N),'MinPeakDistance',20,'MinPeakHeight',750);
    Bx=rmoutliers(xpks,'mean');
    [Bx,TFx]=rmoutliers(xpks);
    xpeakmean=mean(Bx);
    xpeakstd=std(Bx);
    xspikes=numel(Bx);
    xHR=numel(xpks);
    findpeaks(xMatrix(:,N),'MinPeakDistance',20,'MinPeakHeight',750);hold on;
    title('filtered ECG x')
    xlabel('Samples')
    ylabel('uV')
    xlim([0 L])
    ylim([-2000 2000])
    %New Matrix
    xpkMatrix(N,1)=xpeakmean;
    xpkMatrix(N,2)=xpeakstd;
    xpkMatrix(N,3)=xspikes;
    xpkMatrix(N,4)=xHR;
end

or new windows:

xMatrix=reshape(x,L,TS/L);
%Filtering
[b,a]=butter(4,[0.0390625 0.46875],'bandpass');       %4th order bandpass butterworth 5-60Hz
xMatrix=filtfilt(b,a,xMatrix);
% filtered ECG Plot x
for N=(1:TS/L)
    %Findpeaks
    figure;plot(xMatrix(:,N));hold on;
    [xpks,locs]=findpeaks(xMatrix(:,N),'MinPeakDistance',20,'MinPeakHeight',750);
    Bx=rmoutliers(xpks,'mean');
    [Bx,TFx]=rmoutliers(xpks);
    xpeakmean=mean(Bx);
    xpeakstd=std(Bx);
    xspikes=numel(Bx);
    xHR=numel(xpks);
    findpeaks(xMatrix(:,N),'MinPeakDistance',20,'MinPeakHeight',750);
    title('filtered ECG x')
    xlabel('Samples')
    ylabel('uV')
    xlim([0 L])
    ylim([-2000 2000])
    %New Matrix
    xpkMatrix(N,1)=xpeakmean;
    xpkMatrix(N,2)=xpeakstd;
    xpkMatrix(N,3)=xspikes;
    xpkMatrix(N,4)=xHR;
end

[sam van Bohemen]

Hi Ridwan

Thanks for your help.

I have attached x as a zip file.

I tried altering my code as you suggested but I still can't view Bx for all windows.

[Ridwan Alam]

Hi Sam,

II tried to run the code without the Bx part, it did generate multiple plot windows showing both the signal and their peaks.

xnew = x(1:end-144);
L = 1000;
TS = length(xnew);
xMatrix=reshape(xnew,L,floor(TS/L));
%Filtering
[b,a]=butter(4,[0.0390625 0.46875],'bandpass');       %4th order bandpass butterworth 5-60Hz
xMatrix=filtfilt(b,a,xMatrix);
for i=1:TS/L
    %Findpeaks
    figure;plot(xMatrix(:,i));hold on;
    findpeaks(xMatrix(:,i),'MinPeakDistance',20,'MinPeakHeight',750);
    title('filtered ECG x')
    xlabel('Samples')
    ylabel('uV')
    xlim([0 L])
    ylim([-2000 2000])
    
%     [xpks,locs]=findpeaks(xMatrix(:,i),'MinPeakDistance',20,'MinPeakHeight',750);
%     Bx=rmoutliers(xpks,'mean');
%     [Bx,TFx]=rmoutliers(xpks);
%     xpeakmean=mean(Bx);
%     xpeakstd=std(Bx);
%     xspikes=numel(Bx);
%     xHR=numel(xpks);
    %New Matrix
%     xpkMatrix(i,1)=xpeakmean;
%     xpkMatrix(i,2)=xpeakstd;
%     xpkMatrix(i,3)=xspikes;
%     xpkMatrix(i,4)=xHR;
end

Please provide details about how far you got (make sure to show whole code) and what issues you are facing.