What’s new in h5py 2.1

Dimension scales

H5py now supports the Dimension Scales feature of HDF5! Thanks to Darren Dale for implementing this. You can find more information on using scales in the dimensionscales section of the docs.

Unicode strings allowed in attributes

Group, dataset and attribute names in h5py 2.X can all be given as unicode. Now, you can also store (scalar) unicode data in attribute values as well:

>>> myfile.attrs['x'] = u"I'm a Unicode string!"

Storing Unicode strings in datasets or as members of compound types is not yet implemented.

Dataset size property

Dataset objects now expose a .size property which provides the total number of elements in the dataspace.

Dataset.value property is now deprecated.

The property Dataset.value, which dates back to h5py 1.0, is deprecated and will be removed in a later release. This property dumps the entire dataset into a NumPy array. Code using .value should be updated to use NumPy indexing, using mydataset[...] or mydataset[()] as appropriate.

Bug fixes

  • Object and region references were sometimes incorrectly wrapped wrapped in a numpy.object_ instance (issue 202)
  • H5py now ignores old versions of Cython (<0.13) when building (issue 221)
  • Link access property lists weren’t being properly tracked in the high level interface (issue 212)
  • Race condition fixed in identifier tracking which led to Python crashes (issue 151)
  • Highlevel objects will now complain if you try to bind them to the wrong HDF5 object types (issue 191)
  • Unit tests can now be run after installation (issue 201)