Additional API Features
*********************** 

In this section we highlight the additional API features and optimisations that ``pyfive`` provides beyond the standard ``h5py`` functionality.

Modifications to the File API
-----------------------------

When acccessing a file, in addition there are two modifications to the standard ``h5py`` API that can be used to optimise 
performance. A new method (``get_lazy_view``) and an additional keyword argument on ``visititems`` (noindex) are provided
to support access to all dataset metadata without loading chunk indices. 

.. note::
   Loading chunk indices at dataset instantiation is mostly a useful optimisation, but not if you have no intent of accessing the data itself.

The ``Group`` API is fully documented in the autogenerated API reference, but the additional methods and keyword arguments are highlighted here.
These methods are also avilable on the ``File`` class, since ``File`` is a subclass of ``Group``. 

.. automethod:: pyfive.high_level.Group.get_lazy_view
.. automethod:: pyfive.high_level.Group.visititems
   :noindex:

Modifications to the DatasetID API
----------------------------------

When accessing datasets, additional functionality is exposed via the ``pyfive.h5d.DatasetID`` class, which implements the low-level data access methods for datasets (`Variables`).

The ``DatasetID`` API is fully documented in the autogenerated API reference, but additional methods and attributes are highlighted here:

.. autoattribute:: pyfive.h5d.DatasetID.first_chunk
.. autoattribute:: pyfive.h5d.DatasetID.btree_range
.. automethod:: pyfive.h5d.DatasetID.set_pseudo_chunk_size