MATLAB: How to read text file into formatted array

datetime data format

I have a text file which contains many rows of this shape

    '0862;1;10/09/2002;09:15:59;23.845089;38.018470;486253.80;4207588.10'

I need to read each line in different cells. each cell contains data between ";" and the third and forth one are date and time while others are double numbers.

would you please help me to do so

Best Answer

Here is a function, which does what I believe is what you want. The third column of out is a serial date number.

    >> out = cssm('cssm.txt')
    out =
       1.0e+06 *
        0.0009    0.0000    0.7315    0.0000    0.0000    0.4863    4.2076
        0.0009    0.0000    0.7315    0.0000    0.0000    0.4863    4.2076
        0.0009    0.0000    0.7315    0.0000    0.0000    0.4863    4.2076
    >> datestr( out(:,3), 31 )
    ans =
    2002-10-09 09:15:59
    2002-10-09 09:15:59
    2002-10-09 09:15:59

where

    function    out = cssm( filespec ) 
        fid = fopen( filespec );
        cac = textscan( fid, '%f%f%s%s%f%f%f%f'              ...
                     , 'Delimiter',';', 'CollectOutput',true );
        fclose( fid );
        str = cell2mat(cac{2});
        sdn = datenum( str, 'mm/dd/yyyyHH:MM:SS');
        out = cat( 2, cac{1}, sdn, cac{3} );    
    end

and where cssm.txt contains

    0862;1;10/09/2002;09:15:59;23.845089;38.018470;486253.80;4207588.10
    0862;1;10/09/2002;09:15:59;23.845089;38.018470;486253.80;4207588.10
    0862;1;10/09/2002;09:15:59;23.845089;38.018470;486253.80;4207588.10

Related Solutions

MATLAB: How to make a permanent change to a matrix using sortrows

 P = sortrows(P,7) ;

Most of the time functions don't operate "externally", so SORTROWS doesn't alter your array P defined in the workspace. It creates a new sorted array that it outputs. You have to store this output back into P if you want P to be the sorted version. If you wanted to keep the original, you could store it into a new variable:

 P_sorted = sortrows(P,7) ;

MATLAB: Reading big textfile with textscan

Solution One

You do not need to delete the first ten rows from the file, because textscan has an option to ignore header lines, so you can use this instead:

Out = textscan(....,'HeaderLines',10);

To read 1280 columns of data you need to define this in the format string, so the final code could be something like this:

fmt = repmat('%f',1,1280);
fid = fopen('textfile.txt','rt')
out = textscan(fid, fmt, 'Delimiter',',', 'HeaderLines',10);
fclose(fid);

Solution Two

If the data in the matrix is all numeric (note the header lines do not need to be) then you could use the much simpler dlmread instead, something a bit like this:

out = dlmread('textfile.txt',',',10,0);

Examples

% textscan
fmt = repmat('%f',1,5);
fid = fopen('temp.txt','rt');
out_txt = textscan(fid, fmt, 'Delimiter',',', 'HeaderLines',3);
fclose(fid);
out_txt = cell2mat(out_txt)
% dlmread
out_dlm = dlmread('temp.txt',',',3,0)

display this in the command window:

out_txt =
     0     1     2     3     4
     5     6     7     8     9
out_dlm =
     0     1     2     3     4
     5     6     7     8     9

The sample text file that I used is attached here:

Best Answer

Related Solutions

MATLAB: How to make a permanent change to a matrix using sortrows

MATLAB: Reading big textfile with textscan

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