Max Peak Distance (findpeaks)

Hi, I'm using the 'findpeaks' function and i want to insert a min and max limit to the distance between the peaks. In the function there is only the parameter 'MinPeakDistance' and i need the equivalent "maxpeakdistance" too. Any suggestions? Thanks

[Janak Thotakura]

Can you explain what exactly do you mean by 'maxpeakdistance' in finding peaks? An example would be helpful.

Answer 1

[The Matlabinator]

I'm wondering about this too. There's a 'MinPeakDistance' that rejects peaks which are located within some specified distance. Is there an equivalent for peaks located above some threshold value?

Answer 2

[Stefano Francavilla]

I wrote this code, it isn't elegant but I hope could be helpful.

%%1st step - Find a large amount of peaks with non-stringent constraints
x = zeros(N,1); % x-vector (what you want)
y = zeros(N,1); % y-vector (what you want)
minpeakheight = 0; % what you want (fairly small value)
minpeakdistance = 0; % what you want (fairly small value)
[peak_vals,peak_locs] = findpeaks(y,x,'MinPeakHeight',minpeakheight,'MinPeakDistance',minpeakdistance);

ref = 0; % reference (what you want)
mpd = ref*0.9; % min peak distance (what you want)
MPD = ref/0.9; % Max Peak Distance (what you want)

%%2nd step - Find 1st peak
[~,index] = max(peak_vals(peak_locs<peak_locs(1)+mpd)); % index of the 1st peak
new_peak_locs = peak_locs(index); % position of the 1st peak
new_peak_vals = peak_vals(index); % value of the 1st peak

%%3rd step - Find other peaks
while peak_locs(end)>new_peak_locs(end)+mpd
    index = find(peak_locs>new_peak_locs(end)+mpd & peak_locs<new_peak_locs(end)+MPD);
    [~,jj] = max(peak_vals(index));
    new_peak_locs(end+1) = peak_locs(index(jj)); % peaks position vector
    new_peak_vals(end+1) = peak_vals(index(jj)); % peaks value vector
end

[Devendra]

Thank you very much for providing very helpful matlab code to matlab community. I am very much eager to use your code on my NDVI time series data. I am attaching the NDVI data and my humble request to you please suggest me how to use your code on my data file. Further my thresholds for peaks height is 0.4 (NDVI value greater than 0.4) and distance is 60 days. With these constraints I want to find out number of peaks and they must be stored in a vector.

I would be highly obliged to you for your kind cooperation. Devendra