.. module:: emma.io

.. toctree::
   :maxdepth: 2
   :caption: Contents:


I/O
==================

Travel analyses often use information about thousands of zones and record
information for all possible origin-destination pairs, generating large
matrices. It is often impossible to allocate enough memory to store these
large datasets or perform analytical tasks with them. Moreover, while 
in-memory operations are performant, many matrices' data must persist across
numerous processes. Emma uses the H5 file format and pytables to store arrays
on-disk and efficiently consume and manipulate these data for travel analysis.
The io module provides classes and functions to make these operations as
seamless as possible.

**Classes and Functions**
- `H5Array`: A class that manages connections to an H5 file. Users do not
  need to implement this class directly. Rather, the `LbArray` and `Skim`
  classes use it when their `data` attributes refer to on-disk arrays in
  H5 files.

- `initH5Array`: A function that initializes an on-disk array. Users do
  no need to call this function directly. Rather, the `LbArray` and `Skim`
  classes use it to intialize on-disk arrays in H5 files as need when
  setting their `data` attributes.

- `listH5Nodes`: A convenient function for viewing the contents of an
  H5 file.

- `sparseToHDF`/`loadSparse_HDF`: basic functions to support the storage
  and loading of sparse matrices in H5 files.

H5Array
---------
.. autoclass:: H5Array
    :members:


Functions
----------
.. autofunction:: listH5Nodes


.. autofunction:: sparseToHDF


.. autofunction:: loadSparse_HDF




* :ref:`genindex`
* :ref:`modindex`
* :ref:`search`