Apply 'findpeaks' in every column

Hi guys, i have a problem.

I have a (1200x600) matrix, where each column consists on a trace with at least 3 peaks, and i want to find the 3 maxpeaks in every column.

For the first trace (first column) the following code gives me the 3 max values:

Pilant_Vy_env = xlsread('Pilant_Vy_env.xlsx'); %The matrix is in .xlsx matlab spreadsheet format
first = Pilant_Vy_env(:,1);
[PKS,locs,~,prm] = findpeaks(first); %'first' is the first column of the matrix
[~,i] = sort(prm,'descend');
MAX = first(locs(i(1:3)));
plot(1:numel(first),first,'-',locs(i(1:3)),MAX,'o ')

What should i do if i want to use it for all the others 599 columns?

Thank you for your kind consideration,

Mattia

[KSSV]

Run a loop..

[Mattia Fattori]

Thanks KSSV. If i write the following code, what am i doing wrong?

ncol=size(Pilant_Vy_env);
for k = 1:ncol 
    [PKS,locs,~,prm] = findpeaks(Pilant_Vy_env(:,k));
    [~,j] = sort(prm,'descend');
    MAX = first(locs(j(1:3)));
end
%Error:Index in position 2 exceeds array bounds (must not exceed 600).

I would like to obtain a 3x600 matrix, with the max (first, second and third) in each column.

Thank you

Answer 1

[KSSV]

ncol=size(Pilant_Vy_env,2); 
MAX = zeros(ncol,3) ; 
for k = 1:ncol 
    [PKS,locs,~,prm] = findpeaks(Pilant_Vy_env(:,k));
    [~,j] = sort(prm,'descend');
    MAX(k,:) = first(locs(j(1:3)));
end

[Mattia Fattori]

Hi, i made a mistake previously. In MAX i should have written

MAX=Pilant_Vy_env(locs(j(1:3)))

So substituing that in

MAX(k,:) = Pilant_Vy_env(locs(j(1:3)));

%Here's the code
ncol=size(Pilant_Vy_env,2); 
MAX = zeros(ncol,3) ; 
for k = 1:ncol 
    [PKS,locs,~,prm] = findpeaks(Pilant_Vy_env(:,k));
    [~,f] = sort(prm,'descend');
    MAX(k,:) = Pilant_Vy_env(locs(f(1:3)));
end
plot(1:numel(Zerooff),Zerooff,'-',locs(f(1:3)),MAX(50,:),'o ')

as you suggested. But it finds only the peaks of the first column, where as (for example) in column 50 and also in others columns the max obtained have no sense:

Output without the cicle from column 50 (right)

Output from the code with cicle (column 50)..(No sense).

I have no idea...What could be the problem?

Best regards