MATLAB: Textscan with blocks of data with headers to individual block

textscan

Hi All,
I am trying to extract to following data with textscan. But I am not able to implement it correctly. Each block consists of 11 data lines and 8 unnecessary lines to exclude.
Data file (testdata.dat) is :
Title
Data Header:                                                Time:     100.16064 Sec       10/8/2012 3:32:17 PM
Data Acquisition: T
Station Name: default
Test File Name: 
Axial  Axial  Axial 
segments  mm        kN
0         -0.19470811 -0.0067140702
0         -0.19806515 -0.0033570339
0         -0.19806515 -0.0033570339
0         -0.19470811 -0.0067140702
0         -0.16785182 -0.0033570339
0         -0.16785182 -0.0067140702
0         -0.13763849 -0.0067140702
0         -0.12421035 -0.0067140702
0         -0.10742517 -0.0033570339
0         -0.11413924 -0.0033570339
0         -0.14099553 -0.0033570339
Data Header:                                                Time:     100.16064 Sec       10/8/2012 3:32:17 PM
Data Acquisition: T
Station Name: default
Test File Name: 
Axial  Axial  Axial 
segments  mm        kN
0         -0.16785182 -0.0033570339
0         -0.20813625 -0.0067140702
0         -0.2316355 -0.0067140702
0         -0.25513476 -0.0067140702
0         -0.29206216 -0.0033570339
0         -0.35584584 -0.0067140702
0         -0.40620136 -0.0067140702
0         -0.47334209 -0.0067140702
0         -0.55055392 -0.0067140702
0         -0.61098057 -0.0067140702
0         -0.70162052 -0.010071106
My implementation is
fileID = fopen('testdata.dat');
formatSpec = '%d %f %f';
clear C
k = 0;
    N = 11;%Block size
while ~feof(fileID)
  k = k+1;
  C(k,1:3) = textscan(fileID,formatSpec,N,'HeaderLines', 8);%'CommentStyle','##',
end
fclose(fileID)
Please correct my code. Thanks in advance.

Best Answer

Modified version of your code
    fid = fopen('RajRaj.txt');
    formatSpec = '%d%f%f';
    clear C
    k = 0;
    N = 11; %Block size
    while ~feof( fid )
      k = k+1;
      C( k, 1:3 ) = textscan( fid, formatSpec, N, 'HeaderLines', 8 ); 
    end
    fclose( fid );
check the output
    >> whos C
      Name      Size            Bytes  Class    Attributes
      C         2x3              1112  cell
"Please correct my code" &nbsp I didn't try your code and isn't sure why it doesn't work. It's tricky to count header-lines. An ending new-line matters.
&nbsp
Here is another function that uses &nbsp fileread &nbsp and &nbsp regexp
    >> g = read_blocks_of_numerical_data( 'RajRaj.txt', 150 );
    >> g{:}
    ans =
             0   -0.1947   -0.0067
             0   -0.1981   -0.0034
    ...
    ans =
             0   -0.1679   -0.0034
             0   -0.2081   -0.0067
    ...
Where both the function and the sample text file are attached. The magical number &nbsp 150 &nbsp is the minimum number of bytes in a block of numerical data. The entire file must fit in memory together with the result.
&nbsp
And one more function
    >> M = RajRaj()
    M(:,:,1) =
             0   -0.1947   -0.0067
             0   -0.1981   -0.0034
             ...
    M(:,:,2) =
             0   -0.1679   -0.0034
             0   -0.2081   -0.0067
             ...
where
    function  M = RajRaj()
        xpr = '(?<=kN)[ 0-9\.\+\-e\r\n]++(?=(Data Header:)|(\s*$))';
        str = fileread( 'RajRaj.txt' );
        cac = regexp( str, xpr, 'match' );
        M = nan( 11, 3, length( cac ) ); 
        for jj = 1 : length( cac )
           M( :, :, jj ) = str2num( cac{jj} ); 
        end
    end
&nbsp
I believe there is a reason why Matlab doesn't include a good functions to read a file with many blocks of numerical data.
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