FAQ
===

Some frequently asked questions would be shown here. If the error you
met is not contained here, please open an issue on out project
https://github.com/abess-team/abess/issues.

Python package
--------------

Installation failed
~~~~~~~~~~~~~~~~~~~

1. Compliers
^^^^^^^^^^^^

First of all, please check the version of Python and GCC/MSVC. To make sure
that ``abess`` package runs correctly,

-  Python 3.5 or later is required;
-  On Linux and MacOS, GCC 4.7 or later is required (support c++11);
-  On Windows, Microsoft Visual C++ (MSVC) Build Tools is required;

What's more, the newer version is recommended. So if you meet some
errors, please try to update the complier first.

Besides, in Windows, you may receive an error said “*error: Microsoft
Visual C++ \*version\* is required*”. To fix it, you need to check if
MSVC is installed and enabled correctly. That is, to download 
`Microsoft C++ Build Tools <https://visualstudio.microsoft.com/visual-cpp-build-tools/>`__
and install (or re-install) the "Desktop development with C++" module inside.

2. Permission
^^^^^^^^^^^^^

If you receive an error said "*Can't create or remove files in install
directory*" during the installation, this may be caused by permission
denied. The step below would help with it.

-  For Linux/MacOS: run ``$ python setup.py install --user`` or
   ``$ sudo python setup.py install`` instead.
-  For Windows: run ``$ python setup.py install --user`` or
   run the command as an administrator.


3. Dependencies
^^^^^^^^^^^^^^^

If you receive an error message including::

   ...
   Could not find a package configuration file provided by "pybind11" with any
   of the following names:

       pybind11Config.cmake
       pybind11-config.cmake*"
   ...

it means `pybind11 <https://pybind11.readthedocs.io/en/stable/installing.html#>`__ has
not been installed properly, and please check it again.

What's more, this situation usually happen when you install by ``pip install pybind11``.
Instead, we recommend using ``pip install pybind11[global]`` to avoid it.

Import failed?
~~~~~~~~~~~~~~

1. Folder name
^^^^^^^^^^^^^^

Make sure your working folder path is not named “abess”. If not, Python
would not import the ``abess`` packages and give some errors.

Example not reproducible?
~~~~~~~~~~~~~~~~~~~~~~~~~

1. Datasets
^^^^^^^^^^^

Some examples are based on data generated by ``abess.datasets``.
Since it depends on ``numpy.random`` and it would 
`causes differences on a different OS or CPU <https://numpy.org/neps/nep-0019-rng-policy.html>`_,
you might get a different dataset and finally a different result.


R package
---------

-  Update Rcpp package if you encounter the following errors:

.. code:: r

   function 'Rcpp_precious_remove' not provided by package 'Rcpp'