Hi Antonio:
The user block I am referring to is a region at the beginning of the
file that is reserved for user metadata. I pasted the description
from the HDF5 documentation below
(http://www.hdfgroup.org/HDF5/doc1.6/UG/08_TheFile.html). I believe
H5Py added this feature
(http://code.google.com/p/h5py/source/detail?r=8a3010d07e14); however,
I don't see a similar way to do this via PyTables. I suppose I could
use h5py to create a blank HDF5 file with the required user block then
reopen it in PyTables, however, I'd like to minimize code dependencies
and everything I've written is built around PyTables rather than h5py.
Thanks!
Brad
Documentation from HDF5:
User-block size
herr_t H5Pset_userblock (hid_t plist, hsize_t size)
herr_t H5Pget_userblock (hid_t plist, hsize_t *size)
The user-block is a fixed-length block of data located at the
beginning of the file and which is ignored by the HDF5 library. This
block is specifically set aside for any data or information that
developers determine to be useful to their application but that will
not be used by the HDF5 library. The size of the user-block is defined
in bytes and may be set to any power of two, with a minimum size of
512 bytes (i.e. 512, 1024, 2048, etc). This property is set with
H5Pset_userblock and queried via H5Pget_userblock.
For example, if an application was thought to reqire a 4K
user-block, that could be set with the following function call:
status = H5Pset_userblock(fcpl_id, 4096)
The property list could later be queried with
status = H5Pget_userblock(fcpl_id, size)
and the value 4096 would be returned in the parameter size.
On Wed, Jan 18, 2012 at 4:52 PM, Antonio Valentino
<antonio.valent...@tiscali.it> wrote:
> Hi Brad,
>
> Il 18/01/2012 21:49, Brad Buran ha scritto:
>> Is there a way to set the size of the user block when creating a file
>> in PyTables? This would be useful for using PyTables to generate
>> Matlab 7.3 compatible files.
>>
>> Brad
>
> Try to use CArrays and set the chunkshape explicitly
>
> http://pytables.github.com/usersguide/libref.html#tables.File.createCArray
>
> Does it answers your question?
>
>
> best regards
>
>
> --
> Antonio Valentino
>
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