modify a data file using MATLAB?

Hi guys,

I am a beginner of MATLAB. Now I have a series of data files output from Openfoam, in terms of different time step (shown in floowing figure). A

and under each folder I have the data included in the file like below. However I only need the column of x and p for each file.

I would like to integrate the files in one separate file and add a second colum between x and p, by t (t=0.5, 1, 1.5 ....)., shown in following format. I have no experience of modyfing a file. Could you please give me some tips, thanks a lot.

    %x t value
    0 0.5 3000
    1 0.5 3200
    ...
    20 30 3690

[Mathieu NOE]

hello

could you share some of the data file ?

tx

[kimy]

for sure. Thanks for your reply.

Original files are sampleDict.zip whereas the p_gorund.csv is what I want (this file was made manually)

Answer 1

[Mathieu NOE]

so this is it !

hope it helps

see the attached file too - you will need them to have the folders sorted in natural order , which is not what matlab does "naturally" , so to say

main code :

clc
clearvars

S = dir('**/*.raw');
[m,n] = size(S);

%% first we have to sort the folders in natural order - otherwise the time steps
% will not be uniformly increasing
for ci = 1:m
    folders{ci} = S(ci).folder;
    filenames{ci} = S(ci).name;
end

[folders_sort,ndx,dbg] = natsort(folders);
filenames_sort = filenames(ndx);

%% main loop for data extraction and concatenation
outdata = [];
for k = 1:m
    foldername = char(folders_sort(k)) % display in command window the folder name
    filename = char(filenames_sort(k)) % display in command window the file name
    if strcmp(foldername(end-1:end),'\0')
        % do nothing (skip t = 0 results)
    else
        F = fullfile(foldername, filename);
        data = importdata(F, ' ', 2); 
        data = data.data;
        [m,n] = size(data);
        % get the simulation time step value from folder name
        ind = strfind(foldername,'\');
        time_step = str2num(foldername(ind(end)+1:end));
        tmp = [data(:,1) time_step*ones(m,1) data(:,4)]; 
        % now vertical concatenation of all files data
        outdata = [outdata ; tmp];
        
    end
    
end

%% export data
T = array2table(outdata);
T.Properties.VariableNames(1:3) = {'%x','t','p'}  % %x	t	p
writetable(T,'file1.csv')

[kimy]

Thanks a lot.

[Mathieu NOE]

You're welcome

[kimy]

Hi, I met a new problem. Could you please help me to have a look?

[Mathieu NOE]

yes - what's the issue ?

[Rik]

Probably this one?

[kimy]

yes, I have two types of data output (sampleDict and toppressure), but I need rearrange them like the format shown in "finaldata" based on any one of two data file..

[kimy]

Anyone has ideas?