How to extract value from a txt file and replace it

Hello everyone,

I would like to replace three specific values ​​in a .dat file (see rectangle in picture attached). The three lines must keep their structures . This code is contained in a loop because after each change I call an .exe file. The problem is that with each loop, some lines are merged suddenly the precise format of the .dat file is changed and the .exe file crashes.

Here is my code :

pitch=[3.83 6.60  8.70 10.45 12.06 13.54 14.92  16.23 17.47 18.70 19.94 ];
filenamePitch='NRELOffshrBsline5MW_OC4DeepCwindSemi_ElastoDyn.dat';
Fid=fopen(filenamePitch);

%recherche des lignes à modifier
data=textscan(Fid,' %s','Delimiter', '\n');
searchValue= strfind([data{1}], 'BlPitch' );
Index = find(not(cellfun('isempty',searchValue)));
fclose(Fid);

% 
for ii=1:3
    oldvaluePitch{ii}=num2str(data{1}{Index(ii)});
 
    fpitch{ii} = regexprep(oldvaluePitch{ii},'\d+(\.)?(\d+)',num2str(pitch(idx)));
end

% newvaluePitch=num2str(pitch(idx));
% % 
% fpitch = regexprep(fpitch,oldvaluePitch,newvaluePitch);

Fid=fopen(filenamePitch,'r+');
for j=1:29
    line=fgetl(Fid);
end
line=fgetl(Fid);
fprintf(Fid,'%s',fpitch{1});
line=fgetl(Fid);
fprintf(Fid,'%s',fpitch{2});
line=fgetl(Fid)

fprintf(Fid,'%s',fpitch{3});
fclose(Fid)

end

Thank you in advance for help.

[Mathieu NOE]

hello Tom

could you share the dat file as well ? or just that fraction of interest ?

[TOM SALIC]

Hello Mathieu,

Yes I can share the file

Answer 1

[Mathieu NOE]

hello again

this is a first trial

It will change the numerical value before BlPitch on ach of the 3 lines

but I think we have to improve the code if the balnks and tab must be fully respected , which is not the case yet (already when we do the file reading, so maybe there is a new option to pass to textscan)

at least , the number of blanks (in these 3 lines) between the numerical value and the char array BlPitch are the same between the original file and the new file

also here I don't know how you want to change the values so I simply picked the first one of the new value array. that also has to be updated if needed

pitch=[3.83 6.60  8.70 10.45 12.06 13.54 14.92  16.23 17.47 18.70 19.94 ];
filenamePitch='File.txt';
Fid=fopen(filenamePitch);
%recherche des lignes à modifier
data=textscan(Fid,' %s','Delimiter', '\n');
data=data{1};
newdata=data;

searchValue= strfind(data, 'BlPitch' );
Index = find(not(cellfun('isempty',searchValue)));
fclose(Fid);

idx = 1; % ?? logic of data replacement 
% 
for ii=1:length(Index)
    tmp = data{Index(ii)};
    ind = findstr(tmp,'BlPitch');
    % focus on first segment
    tmp2 = tmp(1:ind-1);
    % finding blanks (to keep them)
    indbl = findstr(tmp2,' ');
    % new char array
    nca = [num2str(pitch(idx)) tmp2(indbl) tmp(ind:end)];
    % replace cell content
    newdata{Index(ii)} = nca;
end

% export
writecell(newdata, 'Fileout.txt',"QuoteStrings",0);

[Mathieu NOE]

Came up with a better solution

pitch=[3.83 6.60  8.70 10.45 12.06 13.54 14.92  16.23 17.47 18.70 19.94 ];
filenamePitch='File.txt';

data=readlines(filenamePitch);
newdata=data;

searchValue= strfind(data, 'BlPitch' );
Index = find(not(cellfun('isempty',searchValue)));

idx = 1; % ?? logic of data replacement 
% 
for ii=1:length(Index)
    tmp = data{Index(ii)};
    ind = findstr(tmp,'BlPitch');
    % focus on first segment
    tmp2 = tmp(1:ind-1);
    % finding blanks (to keep them)
    indbl = findstr(tmp2,' ');
    % new char array
    nca = ['	' num2str(pitch(idx)) tmp2(indbl) tmp(ind:end)]; % now includes first tab as in original file
    % replace cell content
    newdata{Index(ii)} = nca;
end

% export
writematrix(newdata, 'Fileout.txt',"QuoteStrings",0);

[TOM SALIC]

Thank you mathieu for your involvement but unfortunately the readlines and writecell functions are linked with the 2020 version of Matlab, and I am on Matlab 2018. I will still try to start from your solution.

[TOM SALIC]

It's work perfectly I just change the last part by :

Fid = fopen(filenamePitch,'w');
fprintf(Fid,'%s\n',newdata{:});
fclose(Fid);

Thank you

[Mathieu NOE]

Hi Tom

find some alternatives for reading (using the attached readfile from FEX : readfile - File Exchange - MATLAB Central (mathworks.com)) and exporting with fprintf

try it and let me know

clc
clearvars

pitch=[3.83 6.60  8.70 10.45 12.06 13.54 14.92  16.23 17.47 18.70 19.94 ];
filenamePitch='File.txt';

data=readfile(filenamePitch);

newdata=data;

searchValue= strfind(data, 'BlPitch' );
Index = find(not(cellfun('isempty',searchValue)));

idx = 1; % ?? logic of data replacement 
% 
for ii=1:length(Index)
    tmp = data{Index(ii)};
    ind = findstr(tmp,'BlPitch');
    % focus on first segment
    tmp2 = tmp(1:ind-1);
    % finding blanks (to keep them)
    indbl = findstr(tmp2,' ');
    % new char array
    nca = ['	' num2str(pitch(idx)) tmp2(indbl) tmp(ind:end)]; % now includes first tab as in original file
    % replace cell content
    newdata{Index(ii)} = nca;
end

% export
C = newdata.';
fid = fopen('Fileout4.txt', 'wt');
fprintf(fid, '%s\n', C{:});
fclose(fid);