find peak in data

hello i need to find peaks in this graph how can i do this

Answer 1

[Star Strider]

Use either the findpeaks or islocalmax funcitons. The islocalmax function returns a logical vector, so to get the numerical indices from it, use the find function.

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[Lior Genfon]

i try this function i need only the top and buttom peaks all the peaks in the middle dont need to consedire

[Star Strider]

I do not have your data, so I cannot write code that applies specifically to it.

Both functions have appropraite name-value pair arguments to select only the highest (or lowest) peak in a particular region. For findpeaks it is 'MinPeakDistance', and for islocalmax and islocalmin it is 'MinSeparation'.

To get the negative peaks with findpeaks, negate the first argument, then negate again to get the actual values —

[pks,plocs] = findpeaks(y, ''MinPeakDistance',100)               % Peaks
[vys,vlocs] = findpeaks(-y, ''MinPeakDistance',100)              % Peaks

PeakVals = pks;
ValyVals = -vlys;

Use the correct values for 'MinPeakDistance'. The location index vectors retain their validity regardless.

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