how to run an index loop while using find function

I have two sets of (time) array. By using the time of red mark(ECG) as indicated in the picture. I'm trying to sweep to the right by fixed range (peakgap) to find the blue mark by using find function with condition RpeakTime<PPG1peakTime<PPG1peakTime+peakgap.

I'm trying to figure it out to use find function with index loop. How can I get the answer data of every red plot in array using for loop.

this is my code but I know it does not work

PPG1Psize = numel(PPG1peakTime);
peakgap = ((PPG1Psize)/(3*tend)); %estimate delay time between each ECG peak

for j=1:numECG
    [rows,columns] = find(PPG1peakTime>RpeakTime(i) & PPG1peakTime<(RpeakTime(i)+peakgap));
end

[Star Strider]

Use the findpeaks (or islocalmax) function to get the peaks and locations of each vector separately (EKG & PPG). Then you can get the relevant time differences from those results.

This would be much easier with your data (individual time vectors and corresponding EKG and PPG values).

[Tipnirin Vajanarat]

Thank you for suggestion. But the problem is I've done using findpeak in earlier code(+filter repeating sample out and etc). in the picture is very ideal case but normally baseline shift a lot pluse there are noise and only findpeak wont do the job so I have to do other procedures in order to get each peak correctly. as you can see in the picture, 12,13 and 15 is true peak, but 14 is not.

In conclusion, my data at this stage will be only coordianate of marks.

Is there any function to find next data within range, return back row/colums and can work with index loop ?

[Star Strider]

My pleasure.

There are several ways to correct a wandering baseline (the easiest in my opinion is to use a highpass filter, or bandpass filter to also remove high-frequency noise).

I cannot help you unless I have a representative sample of your data.

[Tipnirin Vajanarat]

Thank you. I've finished the filtering and marking desired peak.

But I'm stuck at finding a proper function to find A single PPG coordinate near ECG in fixed range and make it work with index loop. it sounds simple but I can not find a proper one.

Can find function work with index loop?

[Image Analyst]

Did you see the last sentence of Star's comment?

[Tipnirin Vajanarat]

However I figure it out. but thank you for all the suggestions! really appreciate it

This is my code

k=1;
for i = 1:(numel(RpeakTime)-1) %% in case that last plot of ECG does not have following PPG
    while PPG1peakTime(k) <=  RpeakTime(i)
        k=k+1;
        if PPG1peakTime(k) >  RpeakTime(i)
            PAT(i) = PPG1peakTime(k) -  RpeakTime(i);
        end
    end
end

PAT = PAT.';

Answer 1

[Star Strider]

‘But I'm stuck at finding a proper function to find A single PPG coordinate near ECG in fixed range and make it work with index loop. it sounds simple but I can not find a proper one.’

You may not need to use a loop, or find.

Try this:

EKGlocs = 1:20:250;                                     % Create EKG R-Wave Locations
PPGlocs = 5+cumsum(randi([15 25], 1, 13));              % Create PPG Peak Locations

PPGdiff = bsxfun(@minus, PPGlocs, EKGlocs);             % Differences Between Argument Vectors
PPGabs = EKGlocs + PPGdiff;                             % Absolute Values Of PPG Peak Indices

This would be easier with your data.

[Tipnirin Vajanarat]

Thank you. This also works

[Star Strider]

As always, my pleasure.