Data extraction with undefined file length

I have a large data file and I want to extract specific data from this file. However, I want to program the system in such a way that I can input the same sort of data file into the program and it will still give the same outcome. So for example, there is a string called

tline =' : W A V E P E R I O D = 3.6000E+01 : ';

within the data file. This string occurs on different locations for different data files. What I want to extract from the data file is 3.6000E+01. What I have got so far (but does not work) is:

A = sscanf(tline,' : W A V E P E R I O D = %1.4e : ');

Regards, Mark.

Answer 1

[per isakson]

Try this

str = fileread( 'lorem.txt' );
cac = regexp( str, '(?<=W A V E P E R I O D =)\s*[\d\.\E\+\-]+', 'match','once' )

it outputs

cac =
 3.6000E+01

where lorem.txt is attached

[Mark van Veenendaal]

Thanks Per,

I have managed to obtain it. Would it also be possible to obtain a matrix in this manner? This would be the string.

ADDED MASS MATRIX                                     
-----------------
      1           2           3           4           5          6

1     1.0000E-02  0.0000E+00  1.0000E-02  0.0000E+00  1.0000E-02  0.0000E+00
2     0.0000E+00  1.0000E-01  0.0000E+00 -1.0000E-03  0.0000E+00 -1.0000E-03
3     1.0000E-02  0.0000E+00  1.0000E+00  0.0000E+00  1.0000E-01  0.0000E+00
4     0.0000E+00 -1.0000E-02  0.0000E+00  1.0000E-03  0.0000E+00  1.0000E-03
5     1.0000E-02  0.0000E+00  1.0000E-01  0.0000E+00  1.0000E-01  0.0000E+00
6     0.0000E+00 -1.0000E-03  0.0000E+00  1.0000E-03  0.0000E+00  1.0000E-02

Where I'm only interested in the following numbers:

1.0000E-02  0.0000E+00  1.0000E-02  0.0000E+00  1.0000E-02  0.0000E+00
0.0000E+00  1.0000E-01  0.0000E+00 -1.0000E-03  0.0000E+00 -1.0000E-03
1.0000E-02  0.0000E+00  1.0000E+00  0.0000E+00  1.0000E-01  0.0000E+00
0.0000E+00 -1.0000E-02  0.0000E+00  1.0000E-03  0.0000E+00  1.0000E-03
1.0000E-02  0.0000E+00  1.0000E-01  0.0000E+00  1.0000E-01  0.0000E+00
0.0000E+00 -1.0000E-03  0.0000E+00  1.0000E-03  0.0000E+00  1.0000E-02

Regards, Mark.

[Stephen23]

Just use textscan.

[Mark van Veenendaal]

Stephen, could you elaborate a little bit more please?

Mark.

[per isakson]

Short answer: NO!

To try to extract that numerical block with regular expression would be a severe waste of time.

If the text file looks "exactly" as in your question this reads it

fid = fopen( 'AddedMass.txt' );
cac = textscan( fid, '%*d%f%f%f%f%f%f', 'Headerlines',4, 'Collectoutput',true )
[~] = fclose( fid );

outputs

cac = 
    [6x6 double]

However, if the string is embedded somewhere in a text file it becomes a bit tricky.