How can I extract a certain numerical value from a text file?

I have run a model in a different program which has produced a large number of .txt files of output data.

I would like Matlab to open each file in turn and extract the value underneath "RF2" which is -4.2694476E+08 in the example below:

   THE FOLLOWING TABLE IS PRINTED FOR NODES BELONGING TO NODE SET ASSEMBLY_SET-RF
  
       NODE FOOT-  RF1            RF2            RM3          
            NOTE
  
          1     -1.3405922E+07 -4.2694476E+08  0.0000000E+00

 MAXIMUM        -1.3406E+07 -4.2694E+08   0.000    
 AT NODE                 1           1           1

The number of interest is on Line 4379 of every text file. I have no problems getting the Matlab code to open each file, but I can't seem to get it to extract the correct number. I would like to jump to Line 4379, get the program to disregard the 1 and the -1.3405922E+07 and ONLY take the -4.2694476E+08. The value of this number of interest is different for each file so I can't just get MATLAB to search for "-4.2694476E+08" each time. The number is ALWAYS in the same place for each of the files.

Would anyone be able to point me to a way of getting MATLAB to extract this number? Many thanks

Answer 1

[Jeremy]

I have written a similar function - something along the lines of

fopen(fid)
while feof ~= 1
    str = fgetl(fid);
    if strcmp(str,'string of the previous line that never changes') == 1
        % The previous two lines will sift through the code line by line 
        % and stop when it gets to the line above the data I want
        str = fgetl(fid);
        [s1 s2] = strtok(str);
        [s3 s4] = strtok(s2);
        [s5 s6] = strtok(s4);
        % strtok will break the line apart word by word
        data = str2double(s5); % when you have the number you want, convert it from a string
        
        % If the line your number is on only has numerical data, just use fscanf
        data = fscanf(fid,'%e',4)
    end
end
fclose(fid)

Maybe there is a more efficient way to do this. But for output files that are not formatted well for functions like readtable, this was the way I did it in college

You can just use fscanf if the line you need to read only has numerical data. Or sscanf to take a string out of the way and then fscanf to read the numbers.

[Matt Waters]

Worked perfectly, thanks very much!