octave-kernel 0.30.3

A Jupyter kernel for Octave.

An Octave kernel for Jupyter
============================

Prerequisites
-------------
`Jupyter Notebook <http://jupyter.readthedocs.org/en/latest/install.html>`_ and GNU Octave_.

It is recommended to also install ``gnuplot`` for Octave to enable inline plotting.

Installation
------------
To install using pip::

pip install octave_kernel

Add ``--user`` to install in the user-level environment instead of the system environment.

To install using conda::

conda config --add channels conda-forge
conda install octave_kernel
conda install texinfo # For the inline documentation (shift-tab) to appear.

We require the ``octave-cli`` executable to run the kernel.
Add that executable's directory to the ``PATH`` environment variable or use the
``OCTAVE_EXECUTABLE`` to point to the executable itself.
Note that on Octave 5 on Windows, the executable is in ``"Octave-5.x.x.x\mingw64\bin"``.

We automatically install a Jupyter kernelspec when installing the
python package. This location can be found using ``jupyter kernelspec list``.
If the default location is not desired, remove the directory for the
``octave`` kernel, and install using ``python -m octave_kernel install``. See
``python -m octave_kernel install --help`` for available options.

Usage
-----
To use the kernel, run one of:

.. code:: shell

jupyter notebook # or ``jupyter lab``, if available
# In the notebook interface, select Octave from the 'New' menu
jupyter qtconsole --kernel octave
jupyter console --kernel octave

This kernel is based on `MetaKernel <http://pypi.python.org/pypi/metakernel>`_,
which means it features a standard set of magics (such as ``%%html``). For a full list of magics,
run ``%lsmagic`` in a cell.

A sample notebook is available online_.


Configuration
-------------
The kernel can be configured by adding an ``octave_kernel_config.py`` file to the
``jupyter`` config path. The ``OctaveKernel`` class offers ``plot_settings``, ``inline_toolkit``,
``kernel_json``, and ``cli_options`` as configurable traits. The available plot settings are:
'format', 'backend', 'width', 'height', and 'resolution'.

.. code:: bash
cat ~/.jupyter/octave_kernel_config.py
# use Qt as the default backend for plots
c.OctaveKernel.plot_settings = dict(backend='qt')


The path to the Octave kernel JSON file can also be specified by creating an
``OCTAVE_KERNEL_JSON`` environment variable.

The command line options to Octave can also be specified with an
``OCTAVE_CLI_OPTIONS`` environment variable. The cli options be appended to the
default opions of ``--interactive --quiet --no-init-file``. Note that the
init file is explicitly called after the kernel has set ``more off`` to prevent
a lockup when the pager is invoked in ``~/.octaverc``.

The inline toolkit is the ``graphics_toolkit`` used to generate plots for the inline
backend. It defaults to ``gnuplot``. The different backend can be used for inline
plotting either by using this configuration or by using the plot magic and putting the backend name after ``inline:``, e.g. ``plot -b inline:fltk``.


Troubleshooting
---------------

Kernel Times Out While Starting
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If the kernel does not start, run the following command from a terminal:

.. code:: shell

python -m octave_kernel.check

This can help diagnose problems with setting up integration with Octave. If in doubt,
create an issue with the output of that command.


Kernel is Not Listed
~~~~~~~~~~~~~~~~~~~~
If the kernel is not listed as an available kernel, first try the following command:

.. code:: shell

python -m octave_kernel install --user

If the kernel is still not listed, verify that the following point to the same
version of python:

.. code:: shell

which python # use "where" if using cmd.exe
which jupyter


Gnuplot Error
~~~~~~~~~~~~~
An error that starts with ``gnuplot> set terminal aqua enhanced title`` can be fixed by
adding ``setenv("GNUTERM","qt");`` to ``~/.octaverc`` on MacOS or by installing
``gunplot-x11`` and using ``setenv("GNUTERM", "X11")``.


Blank Plot
~~~~~~~~~~
Specify a different format using the ``%plot -f <backend>`` magic or using a configuration setting.
On some systems, the default ``'png'`` produces a black plot. On other systems ``'svg'`` produces a
black plot.


.. _Octave: https://www.gnu.org/software/octave/download.html
.. _online: http://nbviewer.ipython.org/github/Calysto/octave_kernel/blob/master/octave_kernel.ipynb