how can i find and mark indexes on my data?

I have an ''ses'' file of 1x144000 size. I converted them into 400x720 arrays with 200 overlap with the code "buffer". Based on this information, I calculated a value (feature) called mean crossing irregularity and this is a 1x720 size file. Based on this calculation, I set the threshold as 0.4. I have created a table with the ones larger than 0.4 as "non-wheeze" and the smaller ones as "wheeze". My aim is to find the indexes of these "wheezes" and mark the "wheezes" in the ''ses'' file with vertical lines, but I cannot find the indexes and therefore I cannot mark them. You can see the codes for all of the calculations and the table of marking wheezes and non-wheezes. Can you help me?

[Rik]

@Serhat Sayim just asked this same question.

Answer 1

[Rik]

The answer is already in your question: you should use the find function on your mci array.

For clarity, here are the contents of that m-file:

ses=structWheeze(2,1).SoundData;
piece = 400;

overlap = 200;
frames = buffer(ses, piece, overlap);

mci=zeros(1,size(frames,2)-1); %if you want to do many trials with different segment lengths and overlap amounts, you need to initialize so that a different trial will not be affected by the previous

for segind = 2:size(frames,2)
    segment=frames(:,segind);
    segment=segment-mean(segment); %since it is "mean" crossing irregularity, we should subtract the mean value if our algorithm finds "zero" crossings
    x = 1:length(segment);
    zci = @(v) find(v(:).*circshift(v(:), [-1 0]) <= 0);
    dy = zci(segment);
    x0=zeros(1,size(dy,1)-1); %you need to initialize to refresh it for every new segment
    for k = 1:size(dy,1)-1
        b = [[1;1] [x(dy(k)); x(dy(k)+1)]]\[segment(dy(k)); segment(dy(k)+1)];
        x0(k) = -b(1)/b(2);
    end
    iz=diff(x0);
    iz(isnan(iz))=[];
    mci(segind)=std(iz)/mean(iz);
end
figure,plot(ses),hold on,plot(resample(mci,144000,length(mci)),'r')
w = strings(size(mci));
w(mci<0.4) = "wheeze";
w(mci>=0.4) = "non-wheeze";
T = table(mci.',w.');

[furkan akhan]

thank you! how can i use find function? could you help me?

[Rik]

What did you try? Did you read the documentation?

doc find

If you have trouble with Matlab basics you may consider doing the Onramp tutorial (which is provided for free by Mathworks).

[furkan akhan]

I read it of course but i still couldn't write ''find'' command according to my own code

[Rik]

If you have completed a basic Matlab tutorial, my hint should be fairly self-explanatory: use find on your mci array:

wheeze_ind=find(mci<0.4);

[furkan akhan]

I've already tried this, you can see the attachment(wheeze_ind.png), but this code shows me where the data in mci is less than 0.4. However, I want to find out what this corresponds to in my 144000 data sample. I mean i wanna find starting and ending indexes of the wheezes on a sound plot. You can see it from attachment. For example between 5 to 13 is wheeze i wanna find its indexes.

[Rik]

Since neither you, nor your classmate attached any data, I can't help you very well.

You can see in the wheeze_ind variable all the indices where there is a wheeze. Those are the indices of wheezes, so I don't understand what your issue is.