MATLAB: Importing only specific entries from a text file to matlab

data importregexp

Hello,

   I am trying to import a text file, but do not need all the information, just only specifics (after the : operator). Here is a sample version of the text file

Select type (A or B or C): C Enter the number of days: 30 Select test type (Reg or Mod): Reg Enter the number of TC's used: 1

The data is a mix of alphanumeric and numeric. So I need something that handle both. Any help will be appreciated. Thanks

Best Answer

Regular expressions are probably your best option. Look at the following:

 >> s = 'Select type (A or B or C): C Enter the number of days: 30 Select test type (Reg or Mod): Reg Enter the number of TC''s used: 1' ;
 >> results = regexp(s, '(?<=:\s+)\S+', 'match')
 results = 
    'C'    '30'    'Reg'    '1'

The second argument in the call to REGEXP is the pattern. Let me know if you need help to understand it.

Related Solutions

MATLAB: Textscan reading file and surrounding text with single quotes

 >> fileContent = 'ABCD 8 10.2' ;                      % Fake content for the ex.
 >> columns = textscan(fileContent, '%s %d %f') ;
 >> class(columns)
 ans =
 cell
 >> size(columns)
 ans =
     1     3

TEXTSCAN outputs a cell array of columns, as shown above (each cell of its output contain a column of data). When the data type/class of a column allows it, the column is stored as a numeric array; it is stored as a cell array otherwise (e.g. for "strings").

Accessing the content of cell 1 of cell array columns (using {}), we get..

 >> class(columns{1})
 ans =
 cell

So cell 1 of columns is a cell array in itself. Cell 1 of this cell array contains the string 'ABCD' (where single quotes are the delimiter for strings). Note that displaying a string (e.g. with DISP which is implicit) in the command window doesn't display delimiters

 >> class(columns{1}{1})        % Element 1 of column 1.
 ans =
 char
 >> columns{1}{1}
 ans =
 ABCD

Columns 2 and 3 are numeric, so the content of cells 2 and 3 of columns are not cell arrays but numeric arrays:

 >> class(columns{3})                   % Numeric array of doubles.
 ans =
 double
 >> class(columns{3}(1))                % Element 1 is a double.
 ans =
 double
 >> columns{3}(1)
 ans =
   10.2000

MATLAB: Is {} used as index array in class

Your question is not related to OOP. Look at the following:

 >> c = {5, {'Hello', 'World'}, struct( 'a', 8, 'b', 9 )} ;
 c = [5]    {1x2 cell}    [1x1 struct]

Here, c is a cell array (an array of cells).

 >> class( c )
 ans = cell

You can index blocks of this cell array using ()-type indexing.

 >> c(1:2)
 ans = [5]    {1x2 cell}
 >> c(1)
 ans = [5]

The latter is the first element of the cell array c, which is a cell in itself.

 >> class( c(1) )
 ans = cell

For extracting the content of this cell, you have to use {}-type indexing.

 >> c{1}
 ans = 5

This time it (the content) is the double 5.

 >> class( c{1} )
 ans = double

Now indexing can be "nested"; c{2} is the content of cell #2 of the cell array c. This content is a cell array in itself, that you can again index with both () and {} whether you want cells or their content.

 >> c{2}
 ans = 'Hello'  'World'
 >> class( c{2}(1) )
 ans = cell
 >> class( c{2}{1} )
 ans = char

Or when the content is a struct..

 >> class( c{3} )
 ans = struct
 >> c{3}.a
 ans = 8

Hope it helps,

Cedric

Best Answer

Related Solutions

MATLAB: Textscan reading file and surrounding text with single quotes

MATLAB: Is {} used as index array in class

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