Am using matlab to detect peaks, how can I use it to find the area under the curve, average of data points between peak and valley, and slope?

Is there a way to do this automatically all at once? I have some data, which I find the peaks of like so:

   Peakdata=TaskData(:,k);
            [Maxima,MaxIdx] = findpeaks(Peakdata,'MinPeakHeight',mean(Peakdata),'MinPeakDistance',10);
            Troughdata=1.01*max(Peakdata)-Peakdata;
            [Minima,MinIdx] = findpeaks(Troughdata,'MinPeakHeight',mean(Troughdata),'MinPeakDistance',10);
            Minima = Peakdata(MinIdx);

I have several different data sets which I do this to and I get a list of all the peaks and troughs in the data (looks kinda like an imperfect sine wave) . I also want to number all peaks and then calculate the average of the data between each peak/trough. As well as the ascent/descent rates (slope) to get from each peak and trough. Then if possible calculate the area under the curve between each peak and trough. So not the hole area like a parabola but half the parabola.

Answer 1

[Image Analyst]

Did you try mean() and sum()? Like

for k = 1 : length(MinIdx)-1
    peakAverages(k) = mean(Peakdata(MinIdx(k):MinIdx(k+1)));
    peakAreas(k) = sum(Peakdata(MinIdx(k):MinIdx(k+1)));
end

I'm assuming you have mins on each side of a max - i.e. like no peak on the edge not enclosed in between with trough mins.

[sal goodman]

Yes I do have the mins and it goes peak-min-peak-min, forever but sometimes there might be one extra min or extra max depending on when the data collection was stopped. . Is there a way to calculate the slope between a peak and a min? or the X axis distance from peak to min and then I can find the slope with that value.

[Image Analyst]

How about (valleyY - peakY) / (valleyX - peakX) ?

[sal goodman]

I am trying to get the code to work (even to just gather up the data points between each peak and valley) but running into an error:

The following error occurred converting from cell to double:
Error using double
Conversion to double from cell is not possible.

Error in Test (line 72)
             peakAverages(:,j) = {Peakdata((MaxIdx(j):MinIdx(j+1)),:)};

And here is the code:

for i = 1:numel(tasknames) %for each test point do the math and find the peaks. tasknames lists the test points. 

      TaskData = cell2mat(task_data(i));

      Peakdata=TaskData(:,4); %data is in the 4th column of my larger data matrix. 
      [Maxima,MaxIdx] = findpeaks(Peakdata,'MinPeakHeight',mean(Peakdata),'MinPeakDistance',10);
       Maxima=Peakdata(MaxIdx);        
      Troughdata=1.01*max(Peakdata)-Peakdata;
      [Minima,MinIdx] = findpeaks(Troughdata,'MinPeakHeight',mean(Troughdata),'MinPeakDistance',10);
       Minima = Peakdata(MinIdx); 

       MinLength = length(MinIdx); 
       MaxLength = length(MaxIdx); 

          %if there is a trough first, I want to take the first peak value
          %index and the second trough value index. Also since there are
          %different numbers of peaks and troughs, I want to make sure that
          %they match in length by always ending on a trough index. 

          %if there is a peak first, or MinIdx is greater than MaxIdx, do
          %normal j = 1 until whichver list of peaks/trouhgs is shorter. 
       if MinIdx(1) < MaxIdx(1)

              if MinLength > MaxLength

              for j = 1 : length(MaxIdx)
               peakAverages(:,j) = {Peakdata((MaxIdx(j):MinIdx(j+1)),:)};
              end

               elseif MinLength == MaxLength

                  for j = 1 : length(MinIdx)
                   peakAverages(:,j) = {Peakdata(MaxIdx(j):MinIdx(j+1),:)};
                  end

               elseif MinLength < MaxLength

                       for j = 1 : length(MinIdx)
                       peakAverages(:,j) = {Peakdata(MaxIdx(j):MinIdx(j+1),:)};
                       end
                   end

       else 
           if MinLength > MaxLength

          for j = 1 : length(MaxIdx)
           peakAverages(j,:) = {Peakdata(MaxIdx(j):MinIdx(j),:)};
          end

       elseif MinLength == MaxLength

          for j = 1 : length(MinIdx)
           peakAverages(:,j) = {Peakdata(MaxIdx(j):MinIdx(j),:)};
          end

       elseif MinLength < MaxLength

           for j = 1 : length(MinIdx)
           peakAverages(:,j) = {Peakdata(MaxIdx(j):MinIdx(j),:)};
           end
           end
       end
  end

Answer 2

[Clara Sánchez del Valle]

I did it this way and it worked for me.

            [max, maxIdx] = findpeaks(Data);
            DataInv = 1.01*max(Data) - Data;
            [min, minIdx] = findpeaks(DataInv);

            maxminIdx = [maxIdx minIdx];
            maxminIdx = sort(maxminIdx);
            maxmin = Data(maxminIdx);