For loop to read in sequentially named .txt files

Question

HC98 2021-12-6

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1604240-for-loop-to-read-in-sequentially-named-txt-files

评论： Alagu Sankar Esakkiappan 2021-12-9

I have a batch of txt files named "0, 2, 4, 6, 8".txt and wondered if there was a way for me to read them all in as one batch using a for loop, maybe something like:

txtFiles = dir('*.txt') ;

N = length(txtFiles) ;

iwant = cell(1,N) ;

for i = 1:N

iwant{i} = importdata(txtFiles(i).name) ;

end

% works if all cells are of same size

M = cell2mat(iwant) ;

pcolor(M) ;

shading interp

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Rik 2021-12-6

That code looks like it should work. What happened when you tried it?

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Answer 1

Alagu Sankar Esakkiappan 2021-12-9

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1604240-for-loop-to-read-in-sequentially-named-txt-files#answer_851185

编辑：Alagu Sankar Esakkiappan 2021-12-9

在 MATLAB Online 中打开

I gather that you're trying to convert numerical data from many text files into a single matrix. The Code given in question's reference would work fine with a slight catch. I presume that you're trying to concatenate data from all text file sources in a Row-by-Row manner. But with the above code, cell2mat function appends in a columnwise manner. i.e, cell2mat combines three 5*3 cell arrays into a single 5*9 array instead of 15*3 array. To resolve this, You may try transposing the cell array before matrix conversion according to the following reference:

M = cell2mat(iwant') ; % Transpose Cell Array before conversion

You might also run into another problem for matrix conversion if the text files also have a Column text header in each file. In this case, cell2mat will not return a numerical matrix as expected but instead returns a structure. You may extract data in such case using the following reference:

for i = 1:N
iwant{i} = importdata(txtFiles(i).name) ; % iwant now contains Column header text data as well
end
iwantStruct = cell2mat(iwant'); % Returns a Structure instead of a matrix
matrixData = vertcat(iwantStruct(1:N).data); % Perform Columnwise concatenation to extract data from Stucture for each file