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how to make unzip faster in matlab?

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sandy
sandy on 28 Aug 2013
Answered: Wouter on 7 Aug 2017
i have 50000 .zip files..i need to unzip and process with the files inside those zip files. i coded to unzip in a loop.but its very slow and taked 2 hr to complete unzip of all 5000 files.any way to speedup the unzipping in matlab?

Answers (5)

Wouter
Wouter on 7 Aug 2017
I had the same issue. Using an external program (7-zip) solved the issue for me. Extracting and repacking 1000+ zip files was > 27x faster than the Matlab unzip function.
Is used it like this to unpack:
sys_cmd_unzip = @(z,d) ['"C:\Program Files\7-Zip\7z.exe" e -y -r -o"' d '" "' z '" *'];
cellfun(@(z,d) system(sys_cmd_unzip(z,d)), all_zip_files, new_zip_file_dirs,'uniformoutput',false)
and like this to repack:
sys_cmd_unzip = @(zd) ['"C:\Program Files\7-Zip\7z.exe" a -y -sdel -tzip -r "' zd '.zip" "' zd '/*";'];
cellfun(@(zfd) system(sys_cmd_unzip(zfd)),new_zip_file_dirs,'uniformoutput',false)
cellfun(@(zfd) rmdir(zfd), new_zip_file_dirs) % remove directory where files where stored.
for the command line options of 7zip, see help of 7z.exe.

David Sanchez
David Sanchez on 28 Aug 2013
You can use external software with " ! ", if you use unzip, then, call it this way:
! unzip your_file.zip
  1 Comment
sandy
sandy on 28 Aug 2013
thanks... this is applicable for one zip file..but how to use this(!) for 5500 files in a loop..it showing error?

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Walter Roberson
Walter Roberson on 28 Aug 2013
Have you considered calling upon an external unzipping program by using system() ?
  1 Comment
sandy
sandy on 28 Aug 2013
this s my code of unzipping for N number of files.(nearly 5500).it took 3hr to finish all process, how can i use system() to access external program..help me
zip_files=dir('*.zip');
for k=1:numel(zip_files)
unzip(zip_files(k).name,'output');
T ='.\Extracted Files.\*.tim';
R='.\Extracted Files.\*.run';
movefile(T,'.\T Files');
movefile(R,'.\R Files');
end

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David Sanchez
David Sanchez on 28 Aug 2013
You can try something like this:
my_zips = dir('*.zip');
for k=1:numel(my_zips)
tmp_str = horzcat('unzip ', my_zips(k).name);
system(tmp_str);
end
This will unzip all your zip files.
  2 Comments
David Sanchez
David Sanchez on 29 Aug 2013
Sometimes you can not reduce any more the time taken to perform some tasks. 5000 files are a whole lot of files to unzip. You say it takes 2 hours to perform the job, that means you are unzipping a file every 1.44 seconds, which is not a long time to unzip a file of small size.

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Patrick Lloyd
Patrick Lloyd on 15 Apr 2015
I understand the post is somewhat old but it may be useful for people looking to speed up their zip extraction. If you don't specifically need every single file in the archive at once, you can use something like:
zip_file = 'foo.zip'
destination_folder = 'C:\foo\bar\'
system(['unzip ' '"' zip_file '"' ' file_inside_to_extract.txt' ' -d ' '"' ...
destination_folder '"'])
The system unzip command (for Windows at least) allows you to pull out specific files from the archive.

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