how do I open files automatically in certain order?(numbers giving me trouble)

Question

yc j 2016-1-27

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https://ww2.mathworks.cn/matlabcentral/answers/265356-how-do-i-open-files-automatically-in-certain-order-numbers-giving-me-trouble

评论： Image Analyst 2022-1-24

采纳的回答： Stephen23

So, say I have these files named 1.0.txt, 1.5.txt, 2.0.txt, 2.5.txt, ... 10.0.txt, 10.5.txt

I am automatically opening the files by loop and do what I have to do with the file.

However, Matlab seems to see the file order starting from the first letter.

There fore, Matlab executes the loop in the order of 1.0.txt, 1.5.txt, 10.0.txt, 10.5.txt, 2.0.txt, 2.5.txt... and so on.

I can I avoid this and make the loop go in the order of 1.0, 1.5, 2.0, 2.5, ... 10.0, 10.5 ?

I am doing fprintf and the order is important for my calculation..

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Answer 1

Stephen23 2016-1-27

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https://ww2.mathworks.cn/matlabcentral/answers/265356-how-do-i-open-files-automatically-in-certain-order-numbers-giving-me-trouble#answer_207574

编辑：Stephen23 2021-4-26

在 MATLAB Online 中打开

You can download my FEX submission natsortfiles to sort the files into the order you want:

S = dir(...);
S = natsortfiles(S,'\d+\.?\d*');
for k = 1:numel(S)
    F = S(k).name % filename
    val = sscanf(F,'%f') % numeric value
    ...
end

And here are your example strings:

>> X = {'1.0.txt','1.5.txt','10.0.txt','10.5.txt','2.0.txt','2.5.txt'}
X = 
    '1.0.txt'    '1.5.txt'    '10.0.txt'    '10.5.txt'    '2.0.txt'    '2.5.txt'
>> natsortfiles(X,'\d+(\.\d+)?')
ans = 
    '1.0.txt'    '1.5.txt'    '2.0.txt'    '2.5.txt'    '10.0.txt'    '10.5.txt'

Do you see that my code puts them into the order that you want? That is why in my last answer I told you to use natsortfiles.

EDIT If the files always contain only one decimal values, and these are always the leading characters of the filename, then this will also work:

>> X = {'1.0.txt','1.5.txt','10.0.txt','10.5.txt','2.0.txt','2.5.txt'};
>> N = cellfun(@(s)sscanf(s,'%f'),X);
>> [~,idx] = sort(N);
>> X(idx)
ans = 
    '1.0.txt'    '1.5.txt'    '2.0.txt'    '2.5.txt'    '10.0.txt'    '10.5.txt'