How to make for loop ?

Question

Negar 2013-10-22

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/91131-how-to-make-for-loop

评论： sixwwwwww 2013-10-22

Hello everyone,

I have a folder (database) containing some wav files , and I want to read each of them to extract some features later. I know how to read each file from the list by wavread, for example the first one would be: [signal,Fs,nbits,opts] = wavread('database/ae/ae_0a01.wav') And the second one: [signal,Fs,nbits,opts] = wavread('database/ae/ae_0a02.wav') and so on. But I can not figure out how to make loop in order to automatically get them loaded one by one. Could anybody help in that case?

Thanks

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Negar 2013-10-22

Oh, forgot to say that I have the file list as txt file 'all files.txt' ... So my question is how to pick this files one after the other ... Thank you

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Answer 1

sixwwwwww 2013-10-22

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/91131-how-to-make-for-loop#answer_100542

编辑：sixwwwwww 2013-10-22

在 MATLAB Online 中打开

Dear Negar, try this:

for j = 1:length(files)
    [signal,Fs,nbits,opts] = wavread(strcat('database/ae/ae_0a0', num2str(j), '.wav'));
end

Or better way is using:

dir

to information about all the files in a particular directory and then read them. See http://www.mathworks.de/de/help/matlab/ref/dir.html

In case you have file names stored in text file you can do as follows:

ID = fopen('filename.txt');
files = textscan(ID, '%s');
fclose(ID)
fileNames = files{:};
for j = 1:length(fileNames)
    [signal,Fs,nbits,opts] = wavread(fileNames{j});
end

I hope it helps. Good luck!

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Negar 2013-10-22

Thank you , but I have a question, in first way,

for j = 1:length(files) [signal,Fs,nbits,opts] = wavread(strcat('database/ae/ae_0a0', num2str(j), '.wav')); end

how to make the file name for file nr.10 and above?

sixwwwwww 2013-10-22

在 MATLAB Online 中打开

In that case you can do like this:

for j = 1:length(files)
    if j <10
        [signal,Fs,nbits,opts] = wavread(strcat('database/ae/ae_0a0', num2str(j), '.wav'));
    else
        [signal,Fs,nbits,opts] = wavread(strcat('database/ae/ae_0a', num2str(j), '.wav'));
    end
end

Good luck!

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Answer 2

Azzi Abdelmalek 2013-10-22

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/91131-how-to-make-for-loop#answer_100541

在 MATLAB Online 中打开

out=cell(9,4);
for k=1:9
   file=sprintf('database/ae/ae_0a0%d.wav')
  [signal,Fs,nbits,opts] = wavread(file) 
  out{k,1}=signal;
  out{k,2}=Fs;
  out{k,3}=nbits;
  out{k,4}=opts;
end