save matrix command works sometimes and sometimes gives error

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Priyank Anilchandra Dhyani 2023-7-21

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评论： Priyank Anilchandra Dhyani 2023-7-27

Hello,

I have been running a script that reads in data from multiple files, add them to a structure, and then save it. The code works just fine. But someitmes, it would give me an error.

Error using save

Unable to write file ColdFlow\Grid Resolution_ReOrder\MultitoSingleBlock\OutputFiles\OutputFilesForVisualization\Bfine.mat: Invalid argument.

Error in CollectData (line 110)

save(strcat(FolderName,'/',Case,'.mat'),'Structure','-v7.3')

If I rerun the script again, the error won't show up.

I do run this script on google drive, when I leave out multiple cases to run overnight, this haapens. I am not sure if this is a sync related issue, or matlab related issue. How do I fix it? I need a relaible code, than I can leave running for days to generate data.

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Bruno Luong 2023-7-23

编辑：Bruno Luong 2023-7-23

在 MATLAB Online 中打开

@Priyank Anilchandra Dhyani if I was you I would never use

addpath(strcat(pwd,'\',FolderName))

This is not robust as pwd can change, and the order of the path matters, multiple files with the same name can be found of different path,etc...

I'm not 100% sure if you have to add the absolute path of the file or the rootpath where the relative path is based on in the search path (meaning pwd).

More importantly I'm not sure how MATLAB search path would behave if for some reason the Google drive losts sync and strcat(pwd,'\',FolderName) become temporary invalid.

If you want to write robust code, this is NOT the way you should do.

I would reduce as much as possible program, context, config, etc.. that depend on google drive, mainly the only thing that remain is the file that you try to read and write.

Priyank Anilchandra Dhyani 2023-7-23

@Bruno Luong I totally agree with you, this can potentially increase a lot of problems in future to trace back the errrors. I will try to minimize the scripts dependency on google drive's sync.

Thank you very much!

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Answer 1

Jan 2023-7-22

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https://ww2.mathworks.cn/matlabcentral/answers/1999203-save-matrix-command-works-sometimes-and-sometimes-gives-error#answer_1276993

Avoid strcat to create a folder name, but use fullfile, which cares for the correct separators.

A try/catch block is the way to go to catch and handle errors.

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Priyank Anilchandra Dhyani 2023-7-22

在 MATLAB Online 中打开

Thanks for your reply. Is there a fucntion similar to strcat? I need that statement, because I have made a script that can run across multiple directories. I need to stich it together with pwd. I have attache a part fo the script.

I am not familiar with try/catch blocks. I will look into it. Thanks!

function CollectData(FolderName,Case)  %Input in string
tic
% Following fours lines for path specification is to ensure that the script
% is running in the desired folder only, and all other folder paths are
% removed. 
restoredefaultpath
addpath(pwd)
cd ..
addpath(strcat(pwd,'\',FolderName))
fprintf('current path is %s\n',strcat(pwd,'\',FolderName))
if isfile(strcat(pwd,'\',FolderName,'\ReyAvg.tec'))  
    fprintf('Reading XYZ data ...\n')
    Structure.XYZ=ReadTecPlotDataXYZ('ReyAvg.tec');               %Also read the XYZ Data
    fprintf('... Finished!\n')
    fprintf('Reading ReyAvg data ...\n')
    Structure.ReyAvg=ReadTecplotDataReyAvg('ReyAvg.tec');
    fprintf('... Finished!\n')
else 
    fprintf('RevAvg.tec not found\n')
end
fprintf('Saving Structure ...\n')
save(strcat(FolderName,'/',Case,'.mat'),'Structure','-v7.3')

Jan 2023-7-25

在 MATLAB Online 中打开

"Is there a fucntion similar to strcat?" - I've suggested fullfile already.

Instead of changing the path, it is safer to work with absolute path names. Replace:

restoredefaultpath
addpath(pwd)
cd ..
addpath(strcat(pwd,'\',FolderName))

by

FullFolder = fullfile(pwd, FolderName);
if isfile(fullfile(FullFolder, 'ReyAvg.tec'))
    ...
end

Priyank Anilchandra Dhyani 2023-7-27

@Jan, I didnt realise fullfile is a function that I can use. Thank you very much, I will makes those changes!

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save matrix command works sometimes and sometimes gives error

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save matrix command works sometimes and sometimes gives error

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