Extract data from text file and save them to 3D array

Hello! I have a small question here. I got some text files in form as following:

08-September-2015  10:44

28 lines in following concentration table = NCONC+1

Conc.  %SD /Cr+PCr  Metabolite     

0.599   2%   0.106 Mac    

2.216   6%   0.393 Ala   

0.000 999%   0.000 Asp 
......

There are some hundred lines following, too. However, I only need the first element from the fifth line (2.216), how can I extract it?

Besides, I have hundreds of this kind of files, from which I need to extract this element from above mentioned place. The files are created from a for loop with three variables. I want to save the extracted elements into a 3D array according to these three variables. Can someone help me on this?

I wrote some codes to open the files, the variables of the for loop are in the codes:

directory= 'C:\Users\karl\Documents\COORD\';

for lb=19:11:30;
    for snr=20:105:230;
        for GC=2.5:0.025:2.55; 

filename = [directory, 'Gln', num2str(lb), 'HzSNR', num2str(snr), 'C' , num2str(GC), 'Mice'];

      fid=fopen(filename);

      fclose(fid);

          end;
      end;
  end;

So, the three variables are lb, snr and GC, the files which contains the data I need are also named in a way after these three variables.

Can someone help me? Thank you very much!

Answer 1

[Walter Roberson]

lbvals = 19:11:30;
num_lb = length(lbvals);

snrvals = 20:105:230;
num_snr = length(snrvals);

GCvals = 2.5:0.025:2.55;
num_GC = length(GCvals)l

Your3DMatrx = zeros(num_lb, num_snr, num_GC);

for lbidx = 1 : num_lb
  lb = lbvals(lbidx);
  lbstr = num2str(lb);

    for snridx = 1 : num_snr
      snr = snrvals(snridx);
      snrstr = num2str(snr);

      for GCidx = 1 : num_GC
        GC = GCvals(GCidx);
        GCstr = num2str(GC); 

        filename = fullfile(directory, sprintf('Gln%sHzSNR%sC%sMice', lbstr, snrstr, GCstr));

        fid = fopen(filename, 'rt');
        datacell = textscan(fid, '%f', 1, 'HeaderLines', 4);
        fclose(fid);

        Your3DMatrx(lbidx, snridx, GCidx) = datacell{1};
      end
    end
  end

[James Lorringer]

Thank you so much @Walter Roberson! You saved my day!

Hi, could you please help me further on this program? Now I need to make a linear fit for each column of data in GC axis of the matrix. (In this 2D plot, y axis is the same as GC in the 3D matrix, on x axis are the values of the extracted data. For example,for each column, there will be three points) Thank you very much!