Run loop for multiple text files

[EDIT: Fri May 27 04:38:19 UTC 2011 - Reformat - MKF]

I want to run a loop, then build a matrix for 8 data files. Error message: Undefined function or variable 'data'. keeps popping up. what do I do?

%Data for BrainZ sample_i, for i=1:8, 
%[Data] -> [N' i] , 24(rows) by 2(col), for BrainZ sample_i, for i = 1:8
%col(1) = Region of Interest sample #, col(2) = mean density (tab delimited data)
%row = all measurements(1:24)

files = dir('*.txt');

for i=1:length(files)
 load(files(i).name);
end

%Re-arrange [Data] to form new matrix [A] 
%[A] -> [N" i]  = 4(rows) by 6(col), of BrainZ sample_i, for i = 1:8
%row = measurement_h, for h = 1:4, from Region of Interest (ROI)
%col = ROI = [mU mM mL bU bM bL]
%Monoc Upper = mU, Monoc Middle = mM, Monoc Lower = mL, Bi Upper = bU, Bi Middle = bM, Bi Lower = bL

for n=1:1:size(data,1)
   if n<=4 
       mU(n)=data(n,2);  
   elseif n>=5 && n<=8  
       mM(n)=data(n,2);
   elseif n>=9 && n<=12  
       mL(n)=data(n,2);
   elseif n>=13 && n<=16  
       bU(n)=data(n,2);
   elseif n>=17 && n<=20  
       bM(n)=data(n,2);
   elseif n>=21 && n<=24 
       bL(n)=data(n,2);
   else
   end;
end;

mU(mU == 0) = [];
mM(mM == 0) = [];
mL(mL == 0) = [];
bU(bU == 0) = [];
bM(bM == 0) = [];
bL(bL == 0) = [];

A = cat(2, mU', mM', mL', bU', bM', bL')

Answer 1

[Oleg Komarov]

data = cell(length(files));   
for ii = 1:length(files)
    data{ii} = load(files(ii).name);
end

data = cat(1,data{:});

[ashley]

Thanks! How do I save matrix A for all eight files, then run the cat function to combine each A?

[Oleg Komarov]

You should replace the snippet in your code.