MATLAB: Read *.mat files inside a zip file without extracting(/unzipping) the zip file

data importextractingread .zipunzippingzipzip files

Hello Everybody

I have several zip files with large sizes, each of them contains at least 500 mat files and each of these mat files is a large matrix containing numbers, e.g. 8000*2000 double.

I don't have enough free space to extract these zip files and then import the data inside these matrices. So, I want to know is there any possibility to read these matrices without unzipping these zip files?

Thank you in advance

Best Answer

https://ch.mathworks.com/matlabcentral/answers/10945-read-files-in-zip-file-without-unzipping#answer_15061

https://ch.mathworks.com/matlabcentral/answers/112027-how-to-read-a-zipped-file-without-unzipping-it

Related Solutions

MATLAB: Selective unzipping of files

You will need to use java if you wish to extract only specified files

You can refer to java documentations at the following link.

ZipFile Java documentation

zipFilename = 'abc.zip';
zipJavaFile  = java.io.File(zipFilename);
zipFile = org.apache.tools.zip.ZipFile(zipJavaFile);
% entries = zipFile.getEntries; % to get all entries then iterate
entry = zipFile.getEntry('abcfolder/abcfile.txt'); % empty if not found
if(~isempty(entry))
    inputstream = zipFile.getInputStream(entry);
    outJavaFile = java.io.File(fullfile(pwd,'abcfolder/abcfile.txt'));
    outStream = java.io.FileOutputStream(outJavaFile);
    copier = com.mathworks.mlwidgets.io.InterruptibleStreamCopier.getInterruptibleStreamCopier;
    copier.copyStream(inputstream, outStream);
    outStream.close();
end
zipFile.close();

MATLAB: How to unzip files using external unzip software

Hi,

I would use JAVA to get what you want, e.g. the following example extract the .txt files in a zip files only (done with R2013b):

    zipFile = org.apache.tools.zip.ZipFile('Untitled1.zip');
    entries = zipFile.getEntries;
    while entries.hasMoreElements
         entry = entries.nextElement;
         entryName = char(entry.getName);
         [~,~,ext] = fileparts(entryName);
         if strcmp(ext,'.txt')
              inputStream  = zipFile.getInputStream(entry);
              fileOutputStream = java.io.FileOutputStream(fullfile(pwd,entryName));
              streamCopier = com.mathworks.mlwidgets.io.InterruptibleStreamCopier.getInterruptibleStreamCopier;
              streamCopier.copyStream(inputStream, fileOutputStream);
              fileOutputStream.close;
              inputStream.close;          
         end
    end
    zipFile.close

UPDATED VERSION FOR SCANNING A FOLDER FOR ZIP FILES AND PROCESS ALL OF THEM

zipfolder = 'C:\Users\fhempel\Desktop\tmp';
extractionfolder = 'C:\Users\fhempel\Desktop\tmp';
zipfiles = dir([zipfolder,'\*.zip']);
for i=1:numel(zipfiles)
    zipFile = org.apache.tools.zip.ZipFile(fullfile(zipfolder,zipfiles(i).name));
    entries = zipFile.getEntries;
    while entries.hasMoreElements
         entry = entries.nextElement;
         entryName = char(entry.getName);
         [~,~,ext] = fileparts(entryName);
         if strcmp(ext,'.txt')
              inputStream  = zipFile.getInputStream(entry);
              if ~exist(fullfile(extractionfolder,zipfiles(i).name(1:end-4)),'dir')
                  mkdir(fullfile(extractionfolder,zipfiles(i).name(1:end-4)))
              end
              fileOutputStream = java.io.FileOutputStream(fullfile(extractionfolder,zipfiles(i).name(1:end-4),entryName));
              streamCopier = com.mathworks.mlwidgets.io.InterruptibleStreamCopier.getInterruptibleStreamCopier;
              streamCopier.copyStream(inputStream, fileOutputStream);
              fileOutputStream.close;
              inputStream.close;          
         end
    end
    zipFile.close
end

Best Answer

Related Solutions

MATLAB: Selective unzipping of files

MATLAB: How to unzip files using external unzip software

Related Question