MATLAB: Plot the result of findpeaks() and original signal on same plot

overlay findpeaks() on top of original signal

The plots of findpeaks() and original signal have different x axes scales,hence I am unable to overlay one on top of the other. Any help with this will be greatly appreciated!

Best Answer

They actually do not have different scales. (We do not have your code, so I am guessing here.) The locations of the peaks returned by findpeaks are indices unless you gave it the x-vector as an argument. You can get the x-axis values with the appropriate reference.

Example —

[pks,locs] = findpeaks(y);
x_peaks = x(locs);
figure(1)
plot(x,y,  x_peaks,pks,'pg')
grid

See if that does what you want.

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MATLAB: Find peak and plot graph from peak

I am not certain what you want to do.

If you want to get the peaks and their indices, request those outputs:

[pks,locs] = findpeaks(pure_brain(:,2));                    % Get Peaks (‘pks’) and Peak Indices (‘locs’)

I have no idea what is in your data file, however if you want to plot them and indicate them, try this:

x = 1:size(pure_brain,1);
figure
plot(x, pure_brain(:,2))
hold on
plot(x(locs), pure_brain(locs,2), '^r')
hold off
grid

MATLAB: Calculate FWHM and area of multiple peak

‘... it gives 1×0 empty double row vector.’

That is most likely because the dependent variable vector (is this ‘y’ in your code?) must be the first argument to findpeaks (link).

Try this instead:

[pks,locs,widths,proms] = findpeaks(y,x);

or preferably, just return the indices of the peaks in the ‘locs’ output with:

[pks,locs,widths,proms] = findpeaks(y);

I find the indices easier to work with.

Best Answer

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MATLAB: Find peak and plot graph from peak

MATLAB: Calculate FWHM and area of multiple peak

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