On Fri, Apr 4, 2008 at 11:33 AM, Jarrod Millman <millman@berkeley.edu> wrote:
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.
Hi Jarrod, Thanks for the reply. Indeed I'm running only N.__version__ '1.0.4.dev4312' 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" ? Thanks, Sebastian Haase