How to extract one data from various mat files to one txt file

Question

Anthony 2022-6-28

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https://ww2.mathworks.cn/matlabcentral/answers/1749710-how-to-extract-one-data-from-various-mat-files-to-one-txt-file

评论： Anthony 2022-6-28

My code generates various mat files. I know how to extract one specific data from mat to txt :

Data = load('data001.mat','Vol');
DataField = fieldnames(Data);
dlmwrite('data.txt', Data.(DataField{1}));

But I do not know how to extract the same 'Vol' data of different data00x.mat to the same data.txt.

Thank you for your help.

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Answer 1

Karim 2022-6-28

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编辑：Karim 2022-6-28

在 MATLAB Online 中打开

assuming you want to append the data to the same text file, you can generate the name of the file in a loop:

numFiles = 10;
for i = 1:numFiles
    currFile = sprintf( 'data%03d.mat', i)
end
currFile = 'data001.mat'
currFile = 'data002.mat'
currFile = 'data003.mat'
currFile = 'data004.mat'
currFile = 'data005.mat'
currFile = 'data006.mat'
currFile = 'data007.mat'
currFile = 'data008.mat'
currFile = 'data009.mat'
currFile = 'data010.mat'

so the full routine would be something like (note that it won't work here since the data files are not attached)

numFiles = 10;
for i = 1:numFiles
    currFile = sprintf( 'data%03d.mat', i);
    Data = load(currFile,'Vol');
    DataField = fieldnames(Data);
    dlmwrite('data.txt', Data.(DataField{1}), '-append');
end
Error using load
Unable to find file or directory 'data001.mat'.

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Anthony 2022-6-28

It worked, thank you so much.

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Answer 2

Nitanshu 2022-6-28

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https://ww2.mathworks.cn/matlabcentral/answers/1749710-how-to-extract-one-data-from-various-mat-files-to-one-txt-file#answer_995570

在 MATLAB Online 中打开

Hi Anthony

Probably you could take a reference from below code.

% where directory name is the name of directory where all your mat files
% are present.
directory_instance = dir('directory_name');
file_names = {directory_instance.name};
[row_size, col_size] = size(file_names);
for i = 1: col_size
    file_name = string(file_names(1, i))
    Data = load(file_name,'Vol');
    DataField = fieldnames(Data);
    dlmwrite('data.txt', Data.(DataField{1}));
end