dlmwrite problem

Can someone help put the final touches to the following code. Im attempting to create a .txt file which has a first row specified by 'header' and then attempting to add 'data' from the second row onwards, 'feat1' should be placed above the first column of 'data' and so on. So far I have attempted to import 'header' first and then use append to import 'data'

clear all
  outfile= '/path/to/file/output.txt';
  data = magic(5);
  header={'feat1','feat2','feat3','feat4','feat5'}; 
  dlmwrite(outfile,header,'delimiter','');
  dlmwrite(outfile,data,'delimiter','\t','-append');

This doesnt work as all of 'header' appears in the first column and by typing '\t' to try and make it tab delimited it inputs a tab between each letter.

I also tried to wirte a loop for importing 'header':

    outfile= '/path/to/file/output.txt';
    data = magic(5);
    header={'feat1','feat2','feat3','feat4','feat5'}; 
for i=1:5;
    dlmwrite(outfile,header{1,i},'delimiter','');
end    
dlmwrite(outfile,data,'delimiter','\t','-append');

This doesn't work as it only stores 'feat5' in the .txt file.

Any advice?

cheers

Answer 1

[Jan]

See help dlmwrite: This function is though to export matrices, but not cell strings. You can use fprintf instead fpr the header:

outfile = '/path/to/file/output.txt';
header={'feat1','feat2','feat3','feat4','feat5'};
data = magic(5);

fid = fopen(outfile, 'w');
if fid == -1; error('Cannot open file: %s', outfile); end
fprintf(fid, '%s\t', header{:});
fprintf(fid, '\n');
fclose(fid);
dlmwrite(outfile,data,'delimiter','\t','-append');

BTW. you can use fprintf directly for the data also instead of dlmwrite:

Fmt = [repmat('%g\t', size(data, 2)), '\n'];
fprintf(fid, Fmt, transpose(data));
fclose(fid);

This is faster than closing the file and re-opening it for appending through dlmwrite.