MATLAB: Parsing a Large Text File into Sections

getlparsetext;

I have a large text file as below:
Run Lat Long Time
1    32  32    34
1    23  22    21
2    23  12   11
2    11  11   11
2    33  11  12
up to 10 runs etc.
So I'm trying to break up each section in the file: section 1, section 2, etc and write it to 10 different text files. File 1 will have data from Run 1. File 2 will have data from Run 2.
Thanks,
Amanda

Best Answer

Hi Amanda,
This should work for you. It just reads the input file one line at a time and prints that line to an output file. If it hits a new "section", it makes a new output file named by that section.
fidIn = fopen('inputFile.txt','r');
oldFirstChars = 'somethingtostart';
fidOut = [];
while 1
    tline = fgetl(fidIn);
    if ~ischar(tline), break, end % Handle the end of the input file
        % Get the string up to the first space
        newFirstChars = regexp(tline, '\d+','match','once');
        % If it's a new "section", make a new file
        if ~strcmp(oldFirstChars, newFirstChars)
            if ~isempty(fidOut)
                % Close the old file first
                fclose(fidOut);                      
            end 
            fidOut = fopen(['outputFile' newFirstChars '.txt'],'w');
            oldFirstChars = newFirstChars;
        end
        % Just print out the line that we just read to the output file
        fprintf(fidOut, '%s\r\n',tline);
    end
  % Clean up any open files
  fclose(fidIn);
  fclose(fidOut);
Related Question