How can I replace a specific number (row/column) in .dat file

I need to use a .dat as an input, so I would like to replace specific row/column element (number) for each iteration. This element is located in the first column in which are numbers and letters (depending on the row), the other columns have only letters.

Do I need to change the file format to another one (.txt for instance), then make the replacement, and finally convert it to .dat again? Which options do I have?

I tried dlmwrite, fwrite and many others but unsuccessfully.

Thank you very much.

Alex

Answer 1

[Laurent]

It depends on how your data is stored in the .dat file.

If it is ASCII, you can load it using

mydata=load(Filename,'-ascii');

Then you can do your replacements and save it using the save command.

[Alexandre]

If I open the file using notepad, there are few lines as a headlines and then different columns.

I tried what you said and I got this error:

Number of columns on line 2 of ASCII file "file loaction" must be the same as previous lines.

(probably because of the headlines)

Thanks!

[Laurent]

OK, in that case you can do something like this (I didn't run it so there could be some small errors and I don't know if it is the fastest solution though):

%open file
fid=fopen(filename);

%go to beginning of the file
fseek(fid,0,-1);

data=[];
while feof(fid)==0 %do it for the complete file
    thisline=fgetl(fid); % get the line of text
    temp=textscan(thisline, '%f %f %f %f'); 
    % reads for example 4 columns of  floating point numbers
    if ~isempty(temp{1})
        data=[data; temp];
    end
end

fclose(fid);

[Alexandre]

Thanks again Laurent!I see that this code alows to load the file (I can see the numbers) but it seems that I am losing the original format of the .dat file, isn't? I say that because if, let's say, I can replace the desired number in the loaded file, then will I be able convert it to a .dat file with the original format only with a number replaced?

To be more accurated this would be a part of my .dat file (opened with notepad). And I want to replace the number of the last two lines in order to work as a new input. Is it really possible?

Thank youy very much!

------- HydroDyn v2.01.* Input File ------------------------

NREL 5.0 MW offshore baseline floating platform input properties

False Echo - Echo the input file data (flag)

---------------------- ENVIRONMENTAL CONDITIONS -----------

          1027   WtrDens        - Water density (kg/m^3)

            20   WtrDpth        - Water depth (meters)

             0   MSL2SWL        - Offset between s

---------------------- WAVES -----------------------------

             2   WaveMod        - Incident

             0   WaveStMod      - Model for 

          3630   WaveTMax       - Analysis 

          0.25   WaveDT         - Time step f

             6   WaveHs         - Significant

            10   WaveTp         - Peak-spectral

"DEFAULT" WavePkShp - Peak-shape spectrum

             0   WvLowCOff      - Low  cut-off 

           500   WvHiCOff       - High cut-off frequency 

             0   WaveDir        - Incident wave 

             0   WaveDirMod     - Directional 

             1   WaveDirSpread  - Wave direction   

             1   WaveNDir       - Number of wave directions  

            90   WaveDirRange   - Range of wave directions 

     123456789   WaveSeed(1)    - First  random seed of incident waves 

    1011121314   WaveSeed(2)    - Second random seed of incident waves [