.. _install:

Installing VICE
+++++++++++++++

The simplest method to install VICE is to pull the source distribution from
PyPI_.
To install the latest version, simply run

::

	$ python -m pip install vice [--user]

from the command line.
Users should add the ``--user`` flag if they do not have administrative
privileges on their current machine; this will install VICE to their
``~/.local`` directory.

.. _PyPI: https://pypi.org/project/vice/

Previous versions available on PyPI can be installed by simply specifying the
version number:

::

	$ python -m pip install vice==<version number> [...]

To speed up the installation process, users can tell ``pip`` to parallelize
compiling VICE across some number of cores using the ``--global-option``
command.
For example, to spread compilation across four cores:

::

	$ python -m pip install vice --global-option="build" --global-option="-j4"

Invoking ``--global-option`` uses legacy behavior for ``pip`` and will generate
warning messages to that effect.
``pip >= 24.0`` will enforce the behavior change.
Future versions of VICE will implement a more standard installation process;
our developers are currently in the process of migrating VICE from the
previously standard ``setup.py`` method to the new ``pyproject.toml`` standard
introduced by `PEP 517`__.
In the meantime, if a parallelized installation is required, we ask that users
simply downgrade (if necessary) to ``pip <= 24.0`` and proceed accordingly.

__ pep517_
.. _pep517: https://peps.python.org/pep-0517/

.. _windows_note:

Designed for systems with a Unix kernel, VICE does not function within a
windows environment.
Windows users should therefore install VICE within the
`Windows Subsystem for Linux (WSL)`__.
We emphasize that the Anaconda prompt provided for Windows is **not** a true
Unix kernel, and therefore will fail to install and run VICE properly.
As long as the call to ``pip`` is ran from within WSL, the proper pre-compiled
binary for Linux systems provided on PyPI_ should install successfully.
A `manual installation`__ on a windows machine must also be ran within
WSL and cannot be conducted with the Anaconda prompt.

__ WSL_
__ `Manual Installation`_
.. _WSL: https://docs.microsoft.com/en-us/windows/wsl/install-win10

Although VICE can in principle be installed and ran on 32-bit hardware (e.g.
i686 CPUs), we strongly discourage running VICE on such machines.
Many of VICE's unit tests, including those which run sanity checks on its
calculations, fail on these machines.

Users who have or would like to modify VICE's source code must conduct a
`manual installation`__.
This also applies to users who would like to install a version of VICE that
is still under development (these can be found on various branches of its
`GitHub repository`__) as well as for versions of python still under
development.

__ `Manual Installation`_
__ repo_
.. _repo: https://github.com/giganano/VICE.git

Although it is generally not advisable to mix package managers, this is not a
concern for VICE.
We do not provide VICE distributions through conda_, though users who typically
install their python packages and manage their computing environments with
conda_ can safely conduct their installation using ``pip``.
`As noted below`__, VICE has no run-time dependencies, meaning that there is no
environment that would need to be solved in the event the installation were
conducted with conda_.

__ `Dependencies`_
.. _conda: https://docs.conda.io/en/latest/

If you have already installed VICE and would like help getting started, we
recommend checking out VICE's tutorial_.
Further usage guidelines can be found :ref:`here <getting_started>`.

.. _tutorial: https://github.com/giganano/VICE/blob/main/examples/QuickStartTutorial.ipynb

.. Contents::

Dependencies
============
VICE has no *primary* run-time dependencies; that is, it does not require any
external software to run properly.
All that is required to run VICE is python itself.
There are however a handful of features which are enabled when certain
dependencies are satisfied, and we recommend users install them to make use of
VICE to its full extent.
These *secondary* dependencies are as follows:

1. dill_ >= 0.2.0
	dill_ allows VICE to save python functions with its output. This makes it
	possible to reconstruct simulations from their output.

2. matplotlib_ >= 2.0.0
	matplotlib_ is necessary for the ``show`` function of the ``output``
	object. This is intended to allow users to visually inspect the results of
	their simulations in ``ipython``, a ``jupyter notebook``, or something
	similar without having to plot it themselves. This is included purely for
	convenience, and is not intended to produce publication-quality figures.

3. NumPy_
	VICE's tutorial_ and example code often make use of NumPy_, but the user
	does not need NumPy_ to use VICE.

.. _dill: https://pypi.org/project/dill/
.. _matplotlib: https://pypi.org/project/matplotlib/
.. _NumPy: https://pypi.org/project/numpy/

A Note on Implementation
------------------------
VICE is implemented in ANSI/ISO C and is wrapped using only standard library
Python_ and Cython_. It is thus independent of the user's version of Anaconda_
(or lackthereof). It is NumPy_- and pandas_-compatible, but neither NumPy_-
nor pandas_-dependent. That is, it will recognize user input from both NumPy_
and pandas_ data types such as the NumPy_ array or the pandas_ dataframe, but
is designed to run independently of them.

.. _Anaconda: https://www.anaconda.com/
.. _pandas: https://pypi.org/project/pandas/


Manual Installation
===================
Users who have modified VICE's source code must compile and install their
updated version manually.
Otherwise, we recommend simply making use of ``pip`` as described above.
If you have already modified VICE's source code or plan to do so, we encourage
you to reach out to one of our :ref:`developers <contributors>` - we'd be happy
to consult with you to help VICE meet your needs!

Though VICE does not have any run-time dependencies, there are a few
compile-time dependencies that must be satisfied to install from source.
They are as follows:

1. Python_ >= 3.8

2. setuptools_ >= 18.0

3. gcc_ >= 4.6 or clang_ >= 3.6

On Mac OS X and Linux architectures, it is likely that one of gcc_ or clang_
come pre-installed.
Users may install with alternative C compilers if they so choose, but VICE is
tested with only gcc_ and clang_.
While a sizable portion of VICE's source code is written in Cython_ and
requires Cython_ >= 3.0 to compile, this should be handled automatically by
setuptools_.
Nonetheless, it is trivial to install it manually via
``python -m pip install Cython>=3.0``.

.. _Cython: https://pypi.org/project/Cython/
.. _Python: https://www.python.org/downloads/
.. _Make: https://www.gnu.org/software/make/
.. _gcc: https://gcc.gnu.org/
.. _clang: https://clang.llvm.org/get_started.html
.. _setuptools: https://setuptools.readthedocs.io/en/latest/

Once the build dependencies are satisfied, download the source code
using a terminal and change directories into the source tree:

::

	$ git clone https://github.com/giganano/VICE.git
	$ cd VICE

From here, users may change to a specific branch if necessary.
For example, VICE's latest development version is on a branch named
``development``, and ``git checkout development`` will take you there.
To then compile and install VICE, simply run:

::

	$ python -m pip install .

Users who do not have administrator's privileges on the system they're
conducting the installation should add the ``--user`` command-line argument,
which will conduct a local installation.
A parallelized build using the ``--global-option`` legacy behavior as described
above is also available when installing manually.

Following the installation, if desired, VICE's unit tests can be run with

::

	$ make tests

This can also be achieved from within python itself:

.. code:: python

	import vice
	vice.test()

If you have issues installing or running VICE, please see the section on
`Troubleshooting Your Build`_. If your installation was successful and you
would like help getting started, usage guidelines can be found
:ref:`here <getting_started>`.


.. Additional Compile Options
.. --------------------------
.. VICE affords users flexibility in specifying how they'd like to compile from
.. source.

.. 1. Parallelization
.. 	Users may spread out the job of compiling VICE across multiple cores via
.. 	the ``[-j N]`` command-line argument.
.. 	For example,

	.. ::

.. 		$ python setup.py build -j 2 install [--user]

.. 	will compile all extensions using 2 cores.
.. 	**Warning**: See `note`__ below regarding parallel installations with the
.. 	gcc_ C compiler.

.. .. __ gcc_parallel_note_

.. 2. Suppress verbose output
.. 	Users may suppress the printing of compiler commands to the consoler with
.. 	the ``[-q --quiet]`` command-line argument.
.. 	For example, when running

	.. ::

.. 		$ python setup.py build --quiet install [--user]

.. 	the only lines printed to the console by the setup.py file will say that
.. 	specific extensions are being cythonized.

.. 3. Individual extensions
.. 	If VICE's source code has already been compiled and is located in the
.. 	``build`` directory, then the entire code base does not need to be
.. 	re-compiled every time a small modification is made.
.. 	The name of the extension, which can be determined via the relative path
.. 	to the file, is all that is required.
.. 	For example, the ``vice.singlezone`` object is linked to VICE's C library
.. 	in the file ``vice/core/singlezone/_singlezone.pyx``, so the name of its
.. 	extension is ``vice.core.singlezone._singlezone``.
.. 	To recompile this extension only and reinstall with all previously
.. 	compiled extensions, simply run

	.. ::

.. 		$ python setup.py build ext=vice.core.singlezone._singlezone install [--user]


Things to Avoid
---------------

.. _gcc_parallel_note:

1. Parallelization with the gcc_ compiler
	Users manually installing VICE with the gcc_ C compiler should avoid
	parallelized installations with ``pip``'s ``--global-option`` legacy
	behavior.
	In practice, the developer's find that gcc_ is not able to successfully
	complete compiling VICE across multiple cores.
	This should be a non-issue for those running Mac OS, as gcc_ must be
	installed and clang_ is the default compiler.
	For those on Linux, however, gcc_ is the default.

.. _simultaneous_note:

2. Simultaneous installations
	Users manually installing VICE from source for multiple versions of python
	should not run the setup.py file in separate terminals simultaneously; this
	will cause one of the builds to fail as they will attempt to write to files
	of the same name.
	Likewise, users should not run the tests for multiple versions of python
	simultaneously; this will almost certainly cause a ``segmentation fault``.

.. _condanote:


Troubleshooting Your Build
==========================
The following are a number of issues that can arise when manually installing
VICE.
If none of these options solve your problem, or if you attempted an
installation with ``pip`` as opposed to installing manually, please open an
issue `here`__.

__ issues_
.. _issues: https://github.com/giganano/VICE/issues

Running the setup.py File Failed
--------------------------------

`Did you attempt your installation on Windows without using WSL?`__
If not, `did you attempt the installation for multiple versions of python
simultaneously?`__
Alternatively, `did you run a parallelized installation using the gcc C
compiler?`__
If none of these solutions apply to your case, please open an issue `here`__.

__ windows_note_
__ simultaneous_note_
__ gcc_parallel_note_
__ issues_


Running the Tests Resulted in a Segmentation Fault
--------------------------------------------------
`Did you run the tests for multiple versions of python simultaneously?`__
If not, please open an issue `here`__.

__ simultaneous_note_
__ issues_


VICE Isn't Running from the Command Line
----------------------------------------
If ``vice`` doesn't run from the terminal after installing, first check that
``python3 -m vice`` runs; the two have the same functionality. If neither
work, then it's likely there was an issue with the installation, and we
recommend rerunning the install process, making sure that the instructions are
followed as closely as possible. If this still does not work, please open an
issue `here`__.

__ issues_

If ``python3 -m vice`` works, but ``vice`` does not, then it's likely that
that command line entry was copied to a directory not on your ``PATH``. The
simplest patch for this issue is to create an alias for ``vice`` mapping it to
the longer command. This can be done by adding the following line to your
``~/.bash_profile``:

::

	alias vice="python3 -m vice"

Then either run ``source ~/.bash_profile`` or restart your terminal for the
alias to take effect.

Alternatively, the proper file can simply be copied to any given directory in
your computer. If this directory is not on your ``PATH``, then your ``PATH``
must be modified to contain this file's new location. For example:

::

	$ cp ./bin/vice ~/.local/bin

This will place the command line entry in the ``~/.local/bin/`` directory,
which can be permanently added to your path by adding

::

	export PATH=$HOME/.local/bin:$PATH

to your ``~/.bash_profile``. As with the alias solution, this will require
either running ``source ~/.bash_profile`` or restarting your terminal to
take effect.

**Note**: If you have installed VICE with the ``--user`` option, it is likely
that VICE has automatically made the above modification to your ``PATH``, and
that either running ``source ~/.bash_profile`` or restarting your terminal is
all that is required after copying the file to ``~/.local/bin``. If you have
copied the file to a different directory, VICE will not have added that file
to your ``PATH``.

More information on modifying your PATH can be found `here`__.

If this does not fix the issue, please open an issue `here`__.

.. _pathvariables: https://unix.stackexchange.com/questions/26047/how-to-correctly-add-a-path-to-path
__ pathvariables_
__ issues_

Compiler Failure
----------------
This is usually an indication that the build should not be ran on multiple
cores, which `is usually the case with the gcc C compiler`__.
If you're installing VICE with ``pip``, simply restart the process without
invoking a parallelized installation.
If you're installing manually from source, first run ``make clean``, and then
restart the process outlined above.

If compiler failures persist, please open an issue `here`__.

__ gcc_parallel_note_
__ issues_

Uninstalling VICE
=================
If you have installed VICE from PyPI_, it can be uninstalled from the terminal
via ``pip uninstall vice``. When prompted, simply confirm that you would like
the files removed. If you have downloaded VICE's supplementary data for use
with the ``milkyway`` object, it is recommended that you remove these files
first by running

.. code:: python

	import vice
	vice.toolkit.hydrodisk.data._h277_remove()

before the ``pip uninstall vice`` command.

If you have installed from source, it is likely that ``pip uninstall vice``
can still achieve the same effect.
Uninstalling manually requires a couple of steps.
First, you must identify the path to the directory that it was installed to.
This can be done by launching python and running the following two lines:

.. code:: python

	import vice
	print(vice.__path__)

Note that there are *four* underscores in total: two each before and after
``path``. This will print a single-element list containing a string denoting
the name of the directory holding VICE's compiled extensions, of the format
``/path/to/install/dir/vice``. Change into this directory, and remove the
VICE tree:

::

	$ cd /path/to/install/dir/
	$ rm -rf vice/

Then, check the remaining contents for an ``egg``. This will likely be of the
format ``vice-<version number>.egg-info``. Remove this directory as well:

::

	$ rm -rf vice-<version number>.egg-info

Finally, the command line entry must be removed. The full path to this script
can be found with the ``which`` command in the terminal:

::

	$ which vice

This will print the full path in the format ``/path/to/cmdline/entry/vice``.
Pass it to the ``rm`` command as well:

::

	$ rm -f /path/to/cmdline/entry/vice

If this process completed without any errors, then VICE was successfully
uninstalled. To double-check, rerunning ``which vice`` should now print
nothing, and attempting to import VICE into python should result in a
``ModuleNotFoundError``.