MATLAB: Write data to specific column in text file

fclosefopentext filewrite

I have this text file created from
I = imread('3.jpg');
i = im2bw(I);
m = max(max(i));
[r c] = find(i == m);
fid = fopen('lalit.txt','wt');
for j=1:length(r)
fprintf(fid,'%f %f\n',r(j),c(j));
end
fclose(fid);
 Now i want to do 
for m = 1:length(r)
z(m) = round((r(m) + c(m))/2);
end
z=z';
Now i want to save this z as third column in the same text file, but without modifying r and c.

Best Answer

The only way you should seriously consider for modifying data in text files is to read in the file and write the modified version to another file, possibly followed by renaming the new file to the old name. Modifying a text file "in place" is tricky and often not possible anyhow.
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