read csv file and output csv file

here i have 3 csv file so i should get 3 csv output file but i only get 1 and E data shouldnt be same but it is...

clc
clear all

datapath = 'I:\A'; 
files = dir(fullfile(datapath,'*.csv'));

for k = 1:numel(files) 
    filename = fullfile(files(k).folder,files(k).name);
    data = readmatrix(filename,"NumHeaderLines",2);

    V = data(:,2);
    I = data(:,3)/(56);

    VVV=V(104:131)*1000/6;
    E=VVV/30;
    
    III=I(104:131);
    [m,n]=size(III);
    k=1;
    for i=1:n
        sig(i)=(III(i)*1000/(4*pi))/(VVV(i)/0.3);
        k=k+1;
    end
    for i=1:n
    P=zeros(m,2);
    P(:,1)=E;
    P(:,2)=sig(i);
    plot(E,sig);
    hold on;
    end

    outfile = fullfile(datapath,['out',num2str(k,'%03d'),'.csv']);
    writematrix(P,outfile)
end

Answer 1

[Voss]

You are overwriting k inside the k for-loop:

for k = 1:numel(files)
    filename = fullfile(files(k).folder,files(k).name);
    data = readmatrix(filename,"NumHeaderLines",2);
    
    % ...
    
    k=1;
    for i=1:n
        sig(i)=(III(i)*1000/(4*pi))/(VVV(i)/0.3);
        k=k+1;
    end
    
    % ...
    
    % now k has the value just calculated from the while loop, not the
    % value given by which iteration of the for loop this is.
    
    outfile = fullfile(datapath,['out',num2str(k,'%03d'),'.csv']);
    writematrix(P,outfile)
end

Instead, use a different variable name for those two different meanings of k, e.g.:

for ii = 1:numel(files)
    filename = fullfile(files(ii).folder,files(ii).name);
    data = readmatrix(filename,"NumHeaderLines",2);
    
    % ...
    
    k=1;
    for i=1:n
        sig(i)=(III(i)*1000/(4*pi))/(VVV(i)/0.3);
        k=k+1;
    end
    
    % ...
    
    outfile = fullfile(datapath,['out',num2str(ii,'%03d'),'.csv']);
    writematrix(P,outfile)
end

[arian hoseini]

thanks i think it fixed the output problem but i have another problem....E...how can i put E and sigma in something like P...cause after i fixed k i got index in position 2...for line 12 (I = data(:,3)/(56);)