How to read a structured text file and create a structure for it in Matlab?

Question

I have a text file which contains results for many time steps. for each time step, some basic info was saved in the first line, followed by a matrix that contains other data for this step. The matrix size can differ at every time step and it is not predefined.

How to create a structure based on such text file?

Thanks in advance!

P.S. the results in text file looks like this:

 time=   4.3750000000000001E-004           3           7           4           1   4.9999989999999998E-004
  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00
  0.0000E+00  0.0000E+00  5.6569E+08  7.5717E+08  5.6569E+08  0.0000E+00  0.0000E+00
  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00
  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00

 time=   5.0000000000000001E-004           3           5           3           0   4.9999989999999998E-004
  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00
  0.0000E+00  0.0000E+00  2.3593E+08  0.0000E+00  0.0000E+00
  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00

 time=   1.8125000000000001E-003           3           3           3           1   1.8749999000000001E-003
  0.0000E+00  0.0000E+00  0.0000E+00
  0.0000E+00  3.9138E+07  0.0000E+00
  0.0000E+00  0.0000E+00  0.0000E+00

Answer 1

Assume each new set for data starts by time= and ends by spaced line, you can use the following code sample:

%Open text file for reading (assume file name is 'Data.txt').
f = fopen('Data.txt', 'r');

%Initialize main (store data) to empty matrix.
main = [];

%Initialize index to 1
i = 1;

while (~feof(f))
    %Read single line from text file (as long string).
    S = fgets(f);

    if (strfind(S, 'time') > 0)
        %Remove 'time= ' from the beginning of S.
        S = strrep(S, 'time=', '');

        %Convert string to array of numbers.
        T = sscanf(S, '%f ');

        %Store vector T to main(i).sub1
        main(i).sub1 = T';

        %Set A to empty matrix - prepare for filling with new data.
        A = [];

        %Read next line from text file (as long string).
        S = fgets(f);        
    end    

    %Convert string to array of numbers.
    L = sscanf(S, '%f ');

    if (isempty(L) || feof(f))
        %Store matrix A to main(i).sub2
        main(i).sub2 = A;

        %Advance i (data index) by 1.
        i = i + 1;
    else
        %In case A is not empty, concatenate T to bottom of A.
        A = [A; L'];
    end
end

%Close file.
fclose(f);

---

Result:

>>main(1)

sub1 =

   4.3750e-04   3.0000e+00   7.0000e+00   4.0000e+00   1.0000e+00   5.0000e-04

sub2 =

           0           0           0           0           0           0           0
           0           0   565690000   757170000   565690000           0           0
           0           0           0           0           0           0           0
           0           0           0           0           0           0           0


>>main(2)

sub1 =

   0.00050   3.00000   5.00000   3.00000   0.00000   0.00050

sub2 =

           0           0           0           0           0
           0           0   235930000           0           0
           0           0           0           0           0


>>main(3)

sub1 =

   0.0018125   3.0000000   3.0000000   3.0000000   1.0000000   0.0018750

sub2 =

          0          0          0
          0   39138000          0
          0          0          0