Then read the file line by line until you find your pattern, then read the section you need until the next block of xy. Something like:
desiredxy = [4 2];
searchpattern = fprintf('x=%d y=%d', desiredxy);
fid = fopen('c:\somewhere\somefile.txt', 'rt');
assert(fid > 0, 'failed to open file');
datacolumn = [];
insection = false;
while true
line = fgetl(fid);
if ~ischar(line)
error('reached end of file before pattern was found');
end
if insection
%in the section of interest
if line(1) == 'x'
%beginning of next section. Done reading. Quit while loop
break;
else
%read number
datacolumn = [datacolumn; str2double(line)]; %#ok<AGROW>
end
elseif strcmp(line, searchpattern)
%not in the section of interest but just found its start
insection = true;
end
end
