MATLAB: Finding Lines in a Large Text File with a Specific Text

large text file

I am trying to read a large text file (>1GB). I only want to read lines that contain a specific text. For example, I want to read every line that contains "<field name="data". Currently I am using fgetl and reading every line, checking if the text is in the line, but it takes too long. Any suggestions?

Best Answer

I found the following code that works well
filetext = fileread('fileread.m');
expr = '[^\n]*fileread[^\n]*';
matches = regexp(filetext,expr,'match');
disp(matches')
but the regexp function is slower than I expected. I ended up using the following method which is significantly faster.
fid = fopen('fileread.m','r');
ftext = textscan(fid,'%s','Delimiter','\n');
fclose(fid);
matches = ftext{1}(contains(ftext{1},'fileread'));
disp(matches)
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