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1

Read files in zip file without unzipping

Asked by Etienne Coetzee on 5 Jul 2011
Latest activity Answered by Brunno Machado de Campos on 11 Jan 2018
Hi there
I have a zip file with about 100 binary files in. I have a routine to read the files into matlab variables. Is there a way that I can read the files directly without unpacking the zip file?
Thanks in advance.
Etienne

  1 Comment

Jan
on 6 Jul 2011
What do you want to do with a zipped variable? Do you want to unzip one of the files only?

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4 Answers

Answer by Bob Hamans on 6 Jul 2011

Hi Etienne. I don't know if I understand your question but you just want to list the zip file contents without unzipping? The following code does just that:
function filelist = listzipcontents(zipFilename)
% Create a Java file of the ZIP filename.
zipJavaFile = java.io.File(zipFilename);
% Create a Java ZipFile and validate it.
zipFile = org.apache.tools.zip.ZipFile(zipJavaFile);
% Extract the entries from the ZipFile.
entries = zipFile.getEntries;
% Initialize the file list.
filelist={};
% Loop through the entries and add to the file list.
while entries.hasMoreElements
filelist = cat(1,filelist,char(entries.nextElement));
end
end

  3 Comments

I added some documentation and submitted the function to the File Exchange
[Move as comment - AU]
Hi Bob
I actualy meant that I would like to read the contents of the files directly without having to unzip the file. It is easy enough to unzip and zip the files. I just wanted to see if there is an alternative.
Regards
Etienne
The comment is ambiguous but the code does list the content WITHOUT unzipping.
In other words:
entries = zipFile.getEntries;
does not unzip the content.
The submission can be found on http://www.mathworks.co.uk/matlabcentral/fileexchange/32089-listzipcontents and this should be included with unzip() as an enhancement.

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Answer by Etienne Coetzee on 6 Jul 2011

Ok, thanks Robert. I will log it as an enhancement.

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Answer by Robert Cumming on 6 Jul 2011

have you seen this thread - you could try what it suggests in your own copy of unzip.m - or send an enhancement request to Mathworks.
Its actually quite easy to update the m file(s):
1. Change the number of accepted input arguments to 3.
2. Handle the third input agument (say a cell array of requested files) or set to default (empty cell array)
3. Pass the 3rd argument into the private function extractArchive
4. In the private function do a strcmp on the entryName and your cell array of requested file(s) - if match found extract, if not skip to next (use continue in the while loop)

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Hi, If anyone is until interested, for zip, on Windows (where I tested):
a = fopen('ZIPFILENAME.zip','r');
c2 = fread(a,'uint8=>uint8');
zipname = char(c2(31:31+c2(27)-1));
zipname = strcat(zipname')

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