How can I get only damping and frequency column?
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My aim is to extract only numeric values in Damping and Frequency column only. The file, from which I am trying to extract data is very large and contains special character, numbers, text and empty lines. Can anyone please suggest me an efficient way to extract the required data?
I hope the images below gives you a better understanding of the data file. Thanks in advance!!
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1032895/image.jpeg)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1032900/image.jpeg)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1032905/image.jpeg)
2 commentaires
Mathieu NOE
le 15 Juin 2022
hello
can you zip the file and try to share it (maybe with Google drive or alike)
Réponse acceptée
Karim
le 15 Juin 2022
Modifié(e) : Karim
le 15 Juin 2022
Hi,
One approach is to read the whole file, seek some specific line, from that line read the data with a delimiter.
See below for the code, note that i changed the extention to .txt in order to run the demo on the site. It will work fine if you chage the fileID to 'flutter_2d_rh_wing_base.f06'
Best regards
fileID = fopen('flutter_2d_rh_wing_base.f06.txt');
% read the whole file, interpret each line as a string
MyText = textscan(fileID, '%s%[^\n\r]', 'Delimiter', '', 'WhiteSpace', '', 'ReturnOnError', false);
% convert the cell array into a string array, for easier indexing
MyText = string(strtrim(MyText{1}));
% use some logic to find the usefull data blocks
% first the start locations
StartLineIdx = contains(MyText, "KFREQ 1./KFREQ VELOCITY DAMPING FREQUENCY COMPLEX EIGENVALUE");
StartLineIdx = find(StartLineIdx) + 1;
% now find the stop locations of each data block
StopLineIdx = contains(MyText, "1 MSC.NASTRAN JOB CREATED ON");
StopLineIdx = find(StopLineIdx) - 1;
% remove some indices that occur before the first start index
StopLineIdx(StopLineIdx<StartLineIdx(1)) = [];
% convert the locations into a single logical array
GetMe = false(size(MyText,1),1);
for i = 1:numel(StartLineIdx)
GetMe(StartLineIdx(i):StopLineIdx(i)) = true;
end
% extract the usefull strings from the data
MyData = MyText(GetMe);
% exchange double spaces into a single space
MyData = regexprep(MyData, '\s+', ' ');
% use the spaces to split each string
MyData = split(MyData,' ');
% convert the strings into a numeric array
MyData = str2double(MyData);
% extract the columns of intrest
MyDamp = MyData(:,4);
MyFreq = MyData(:,5);
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