Trying to pass a variable name for a file in a for loop to xlsread

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Mark Bodner 2021-9-26

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https://ww2.mathworks.cn/matlabcentral/answers/1461114-trying-to-pass-a-variable-name-for-a-file-in-a-for-loop-to-xlsread

编辑： Jan 2021-9-27

I'm trying to use xlsread to open a variable filename on each iteration of a for loop. The code I initially used was

for vj=1:prime_file_num
    BaseName='15_File_';
    k=prime_file_num1(vj,1);
    FileName=[BaseName,num2str(k)];
    [~,~,rawS] = xlsread(FileName);

which worked for one iteration, then just seemed to grind away forever trying to read the next File, and now just grinds even on the first iteration. I tried changing the code to

    for vj=1:prime_file_num
        BaseName='15_File_';
        k=prime_file_num1(vj,1);
        FileName=[BaseName,num2str(k)];
        pathname = 'C:\Documents\MATLAB\FileName.xlsx';
        [~,~,rawS] = xlsread(pathname);

But that just returns the error that xlsread can't find the file--its trying to open a file named 'C:\Documents\MATLAB\FileName.xlsx, rather than '15_File_2' for example.

Can anybody tell me what I'm doing wrong or is what I'm trying even possible. Thanks

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Mark Bodner 2021-9-26

Also tried the code and its still just trying to open a file calle 'C:\Documents\MATLAB\FileName.xlsx'. Its not treating it as a path but rather as the file name itself. So there's obviously something missing?

Stephen23 2021-9-27

编辑：Stephen23 2021-9-27

"so does this still work?"

Yes. Look at the code: it uses prime_file_num1 to define the values used in the filenames.

"So there's obviously something missing?"

Make sure that pathname does not include "Filename.xlsx" : check my previous comment again!

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Answer 1

Jan 2021-9-26

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1461114-trying-to-pass-a-variable-name-for-a-file-in-a-for-loop-to-xlsread#answer_795649

编辑：Jan 2021-9-27

在 MATLAB Online 中打开

pathname = 'C:\Documents\MATLAB\FileName.xlsx';

This is a fixed CHAR vector and does not consider the variable FileName.

Stephen's appraoch is working, if the path name is fixed:

BaseName = '15_File_%d.xlsx';  % [EDITED, file extension added]
pathname = 'C:\Documents\MATLAB\';
for vj = 1:prime_file_num
    filename   = sprintf(BaseName, prime_file_num1(vj, 1));
    file       = fullfile(pathname, filename);
    % [~,~,rawS] = xlsread(file);
    disp(file);   % For testing
    ...
end

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Mark Bodner 2021-9-26

For whatever reason, that doesn't work! It just keeps trying to open a file called 'C:\Documents\MATLAB\15_File_2'. It doesn't see anything as a pathway, but rather as the name of the file trying to be read, and then returns the error that the file is not found. I don't know what is going wrong.

Jan 2021-9-27

编辑：Jan 2021-9-27

No, my code does not open anything. It displays the file names only. This means, that you are doing something else and I cannot know, what it is.

Solve the problem step by step. Start with the shown code. Does it work? Do you see the different file names? If all filenames are equal, you have shown, that prime_file_num1 contains only the value 2.

Please post the output of the above code, if you get any problems there.

If this is working proceed with the next step to uncomment the xlsread() command. Do you get an error message now? If so, please post a copy of the complete message.

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