MATLAB Central Newsreader - unzip/gunzip into memory

unzip/gunzip into memory

Fri, 28 Nov 2008 09:31:03 -0500

Hi,

I would like to unzip/gunzip a file into memory instead of writing it to a file first and then
having to read it in again. Is this possible ?
I had a look at the gunzip command and it involves java, can I get to the unzipped data before it is written to file ?

Thanks !

Re: unzip/gunzip into memory

Yuri Geshelin — Fri, 28 Nov 2008 13:30:19 -0500

"E " <ehelden@hotmail.com> wrote in message <ggodom$65o$1@fred.mathworks.com>...
> Hi,
>
> I would like to unzip/gunzip a file into memory instead of writing it to a file first and then
> having to read it in again. Is this possible ?
> I had a look at the gunzip command and it involves java, can I get to the unzipped data before it is written to file ?
>
> Thanks !

Hi

I don't think it is possible. What prevents you from reading the file from disk immediately after gunzipping it? Surely not the lack of disk space. If the time constraints are issue, try virtual drive. This is not matlab topic.

Re: unzip/gunzip into memory

Walter Roberson — Fri, 28 Nov 2008 15:29:32 -0500

E wrote:

> I would like to unzip/gunzip a file into memory instead of writing it to a file first and then
> having to read it in again. Is this possible ?

Yes, you could write a mex interface to zlib.

Alternately, you could mmap the output file. It will still be written to disk, but it
would also be available in memory.

--
.signature note: I am now avoiding replying to unclear or ambiguous postings.
Please review questions before posting them. Be specific. Use examples of what you mean,
of what you don't mean. Specify boundary conditions, and data classes and value
relationships -- what if we scrambled your data or used -Inf, NaN, or complex(rand,rand)?

Re: unzip/gunzip into memory

Ljubomir Josifovski — Tue, 06 Jan 2009 11:56:25 -0500

On 28 Nov 2008, 15:29, Walter Roberson <rober...@hushmail.com> wrote:
> E wrote:
> > I would like to unzip/gunzip a file into memory instead of writing it to a file first and then
> > having to read it in again. Is this possible ?
>
> Yes, you could write a mex interface tozlib.

Somewhat related - does anyone know of a Matlab native implementation
of zlib?
(say analogous to csharp native implementation
http://www.icsharpcode.net/OpenSource/SharpZipLib/ etc)

I expect unlikely but thought I'd better ask.

Thanks in advance,
Ljubomir