How to skip every second file in directory for for loop

Question

Louise Wilson 2020-4-27

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/521222-how-to-skip-every-second-file-in-directory-for-for-loop

评论： Louise Wilson 2022-8-24

I have a folder of .wav files which I am cutting to a shorter length and then re-writing. I would like to do this for every second file in the directory.

How can I adapt my code to do this?

direcName = 'H:\SoundTrap\wav\New folder\*.wav'; %folder                                                
directory = dir(direcName); %all files in folder
[pathstr,name,ext] = fileparts(direcName);
for i=1:length(directory)
    usefile = directory(i).name;                                       
    fileName = strcat(pathstr,'\',usefile);                              
    [y, Fs] = audioread(fileName,[1 2]);                      
    
    startpos = 4 * Fs; %start position in seconds
    endpos = 119 * Fs; %end position in seconds
    % Store edited version
    [ynew, Fs] = audioread(fileName, [startpos endpos]); %read in section of file
        
    % Write new file
    [pathstr,name,ext] = fileparts(fileName);
    folder='H:\SoundTrap\wav\New folder\Cut files';
    outFileName = strcat(folder, '\', name, '.cut',ext);
    audiowrite(outFileName, ynew, Fs);
end

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Stephen23 2020-4-28

在 MATLAB Online 中打开

You can improve the code by using fullfile rather than concatenating strings, e.g. replace this:

fileName = strcat(pathstr,'\',usefile);

with

fileName = fullfile(pathstr,usefile);

Louise Wilson 2020-4-28

Thanks Stephen! Updated to answer re:Image Analyst, all good!

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Answer 1

Louise Wilson 2020-4-28

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/521222-how-to-skip-every-second-file-in-directory-for-for-loop#answer_428795

在 MATLAB Online 中打开

The answer is...

direcName = 'H:\SoundTrap\wav\New folder\*.wav'; %folder                                                
directory = dir(direcName); %all files in folder
[pathstr,name,ext] = fileparts(direcName);
for i=1:2:length(directory)
    usefile = directory(i).name;                                       
    fileName = fullfile(pathstr, usefile);                              
    [y, Fs] = audioread(fileName,[1 2]);                      
    
    startpos = 4 * Fs; %start position in seconds
    endpos = 119 * Fs; %end position in seconds
    % Store edited version
    [ynew, Fs] = audioread(fileName, [startpos endpos]); %read in section of file
        
    % Write new file
    [pathstr,name,ext] = fileparts(fileName);
    folder='H:\SoundTrap\wav\New folder\Cut files';
    outFileName = strcat(folder, '\', name, '.cut',ext);
    audiowrite(outFileName, ynew, Fs);
end

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Benjamin Colbert 2022-8-24

To modify this to skip 23 files (e.g., read one file per day), would you simply change for i=1:2:length(directory) to for i=1:24:length(directory)

Louise Wilson 2022-8-24

Yes, that will select every 24th item of i. Run the first couple of iterations and check it's selecting what you think it is/want it to. It will only work to select one file per day if you have 24 files per day.

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