measuring duration of peaks

Question

Martina Khunova 2023-4-23

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1951883-measuring-duration-of-peaks

评论： Martina Khunova 2023-4-24

Hello, I have an biological signal which I want to know the duration of its peaks. I have tried detecting the peaks and then running down the slope until it turns around. The problem is that index of left side is equal to peak index (shown in the pictures). Do you have any ideas how to solve this?

Thank you :)

this is my code:

[peakValues, indexesOfPeaks] = findpeaks(y,'MinPeakHeight',1.8e6);
numPeaks = length(peakValues);
peakLeft = ones(1, numPeaks);
peakRight = ones(1, numPeaks);
figure(1);
plot(y(:,1), 'b-', 'LineWidth', 1);
hold on;
scatter(indexesOfPeaks, peakValues, 'or');
grid on;
% Find valley to the left of the peak
hold on;
for k = 1 : numPeaks
    for k2 = indexesOfPeaks(k) : -1 :1
        if y(k2+1) < y(k2)
            break;
        end
    end
    peakLeft(k) = k2;
end
% Find valley to the right of the peak
for k = 1 : numPeaks
    for k2 = indexesOfPeaks(k) : length(y)
        if y(k2+1) > y(k2)
            break;
        end
    end
    peakRight(k) = k2;
end
% Plot red lines on the left and red lines on the right.
for k = 1 : length(peakLeft)
	xline(peakRight, 'Color', '#52FFF6', 'LineWidth', 1);
    xline(peakLeft, 'Color', '#FFA5A5', 'LineWidth', 1);
end

this is signal filtration I use:

y_bp = bandpass(signal,[10 21],fs);       
y2 = y_bp.^2;      
Lich_vz=round(100*fs/2200);
b2=fir1(Lich_vz, 3/(fs/2), 'low');
y=filtfilt(b2,a,double(y2));

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Answer 1

Image Analyst 2023-4-23

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1951883-measuring-duration-of-peaks#answer_1221603

在 MATLAB Online 中打开

Try

% Find valley to the left of the peak
hold on;
for k = 1 : numPeaks
    % Start just to the left of the peak by one index.
    startingIndex = indexesOfPeaks(k) - 1;
    for k2 = startingIndex : -1 :1
        if y(k2-1) > y(k2)
            % The signal turned around and started heading back up.
            break;
        end
    end
    peakLeft(k) = k2;
end