[Numpy-discussion] Efficient reading of binary data
Fri Apr 4 05:12:58 CDT 2008
On Fri, Apr 4, 2008 at 11:33 AM, Jarrod Millman <firstname.lastname@example.org> wrote:
> On Fri, Apr 4, 2008 at 1:50 AM, Sebastian Haase <email@example.com> wrote:
> > Hi,
> > Accidentally I'm exactly trying to do the same thing right now .....
> > What is the best way of memmapping into a file that is already open !?
> > I have to read some text (header info) off the beginning of the file
> > before I know where the data actually starts.
> > I could of course get the position at that point ( f.tell() ) close
> > the file, and reopen using memmap.
> > However this doesn't sound optimal to me ....
> > Any hints ?
> > Could numpy's memmap be changed to also accept file-objects, or there
> > a "rule" that memmap always has to have access to the entire file ?
> I am getting a little tired, so this may be incorrect. But I believe
> Stefan modified memmaps to allow them to be created from file-like
> object: http://projects.scipy.org/scipy/numpy/changeset/4856
> Are you running a released version of NumPy or the trunk? If you
> aren't using the trunk, could you give it a try? It would be good to
> have it tested before the 1.0.5 release.
Thanks for the reply. Indeed I'm running only N.__version__
I hope I find time to try the new feature.
To clarify: if the file is already open, and the current position
(f.tell() ) is somewhere in the middle,
would the memmap "see" the file from there ? Could a "normal" file
access and a concurrent memmap into that same file "step on each
others feet" ?
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