Unzip Files

B

Brock

Hi all,

I am new to python, so please don't attack me if this question is easy
or basic. How can I go about extracting the contents of a zip file to
the same directory? Can I extend this question to a zip file that
sits on the internet?

Point being I need to work with the files inside the zipped file, and
there are times when the file is already on my computer, and their
others where the datafile sits on the Internet.

Any help you can provide will be greatly appreciated. In full
disclosure, I usually learn by example and not by trial and error, so
any nudges in the right direction will be greatly appreciated.

Many thanks,

Brock
 
C

Chris Rebert

Hi all,

I am new to python, so please don't attack me if this question is easy
or basic.  How can I go about extracting the contents of a zip file to
the same directory?  Can I extend this question to a zip file that
sits on the internet?

Point being I need to work with the files inside the zipped file, and
there are times when the file is already on my computer, and their
others where the datafile sits on the Internet.

Any help you can provide will be greatly appreciated.  In full
disclosure, I usually learn by example and not by trial and error, so
any nudges in the right direction will be greatly appreciated.

See the extractall() method of ZipFile objects --
http://docs.python.org/library/zipfile.html

Cheers,
Chris
 
T

Tim Chase

I am new to python, so please don't attack me if this question is easy
or basic. How can I go about extracting the contents of a zip file to
the same directory? Can I extend this question to a zip file that
sits on the internet?

While the ZipFile object can take a file-like object, it looks
like it expects to at least be able to seek() on that
file-object. The object you get back from a urlopen() call
doesn't offer a seek(), so you can't directly use this object.

As such, you'd have to (1) download the remote .zip locally or
(2) create your own urlopener (a'la urllib) that has a seek()
method and uses HTTP Content-Range[1] if the server supports it.
Method #1 is fairly easy (especially if the file fits entirely
within memory) but assumes the file isn't gargantuan because
you're slurping the entire file over the network. Method #2
requires much crazier hacking skills but could produce serious
gains if your file was mammoth.
Point being I need to work with the files inside the zipped file, and
there are times when the file is already on my computer, and their
others where the datafile sits on the Internet.

I'd create a wrapper that checks if the passed "filename" is a
URL or a filename. If it's not a local file, download it to a
local tempfile, and then proceed with that file the same as with
the local file, only optionally deleting it when done.

Since the ZipFile can take any file-like that allows for seek(),
memory permitting, you can even read the web-content into a
cStringIO object without having to touch your filesystem.

-tkc

[1]
http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.16
 

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