[Numpy-discussion] Efficient reading of binary data

Jarrod Millman millman@berkeley....
Fri Apr 4 04:33:38 CDT 2008


On Fri, Apr 4, 2008 at 1:50 AM, Sebastian Haase <haase@msg.ucsf.edu> 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.

Cheers,

-- 
Jarrod Millman
Computational Infrastructure for Research Labs
10 Giannini Hall, UC Berkeley
phone: 510.643.4014
http://cirl.berkeley.edu/


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