ANN: HDF5 for Python (h5py) 1.3.1 BETA

HDF5 for Python (h5py) 1.3.1 *BETA*



HDF5 for Python 1.3.1-beta is now available! This release includes numerous
bugfixes and performance improvements, along with support for new versions
of HDF5 and Python. In particular, HDF5 1.8.5 is now supported, along
with Python 2.7 on Windows.

The beta will be available for approximately two weeks. Bug reports and
comments are more than welcome, either at the h5py mailing list (h5py at
googlegroups) or direcly via the bug tracker at

What is h5py?

HDF5 for Python (h5py) is a general-purpose Python interface to the
Hierarchical Data Format library, version 5. HDF5 is a mature scientific
software library originally developed at NCSA, designed for the fast,
flexible storage of enormous amounts of data.

From a Python programmer's perspective, HDF5 provides a robust way to

store data, organized by name in a tree-like fashion. You can create
datasets (arrays on disk) hundreds of gigabytes in size, and perform
random-access I/O on desired sections. Datasets are organized in a
filesystem-like hierarchy using containers called "groups", and
accesed using the tradional POSIX /path/to/resource syntax.

In addition to providing interoperability with existing HDF5 datasets
and platforms, h5py is a convienient way to store and retrieve
arbitrary NumPy data and metadata.

HDF5 datasets and groups are presented as "array-like" and "dictionary-like"
objects in order to make best use of existing experience. For example,
dataset I/O is done with NumPy-style slicing, and group access is via
indexing with string keys. Standard Python exceptions (KeyError, etc) are
raised in response to underlying HDF5 errors.

Highlights in 1.3.1

- Windows binaries now built against NumPy 1.5
- Fix for new identifier behavior means HDF5 1.8.5 is now supported
- Workaround for a serious performance bug in HDF5 relating to chunked data
- Fixed File reference count glitch which caused some one-liners to fail
- Modified atexit hook which conflicted with PyTables
- Support for Cython 0.13
- Fixed conflict between IPython completer and multiprocessing module

Where to get it & where to complain

* Main website, documentation:
* Downloads, bug tracker:
* Mailing list: h5py at


* Linux, Mac OS-X or Windows
* Python 2.5, 2.6 or 2.7
* NumPy 1.0.3 or later
* HDF5 1.6.5 or later (including 1.8); HDF5 is included with
the Windows version.