Pyenv is a platform to install and manage
different versions of Python, isolated from the default Python version.
Its advantage compared to the other options, like Anaconda, is its simplicity and smallness.
Currently, to build BornAgain libraries for different versions of Python,
we use the pyenv platform.
Obtain the installer from https://github.com/pyenv/pyenv-installer.
To install pyenv, use
curl https://pyenv.run | bash
By default, pyenv is installed in $HOME/.pyenv.
The dependencies must be installed before building Python; see https://github.com/pyenv/pyenv/wiki#suggested-build-environment:
sudo apt install build-essential libssl-dev zlib1g-dev \
libbz2-dev libreadline-dev libsqlite3-dev curl \
libncursesw5-dev xz-utils tk-dev libxml2-dev libxmlsec1-dev libffi-dev liblzma-dev
Install pyenv via homebrew:
brew install pyenv
The rest of the pyenv instructions are like those for Linux.
On MS-Windows, pyenv-win should be used.
The available Python versions are distributed as binary, therefore one must choose the version from a given list.
The Python environments are installed by default under %USERPROFILE%\.pyenv\pyenv-win\versions.
To obtain the pyenv root, enter the following in cmd:
echo %PYENV_ROOT%
Obtain a list of available Python versions
pyenv install --list
Obtain a list of available Python versions
pyenv install --list
Install a Python version To install a certain version, say 3.10, use:
pyenv install 3.10
List installed versions
pyenv versions
Obtain the pyenv root folder where all versions are stored
pyenv root
Obtain the path to the current version of Python in pyenv
pyenv which python3
Install Python packages for a certain version of Python
If the path to the Python executable is, for instance, $HOME/.pyenv/versions/3.10.12/bin/python3,
then to install numpy for this specific Python version, one should use
$HOME/.pyenv/versions/3.10.12/bin/python3 -m pip install numpy
To build BornAgain with a specific Python version, the path to the Python platform should be included in CMAKE_PREFIX_PATH variable;
for instance, if Python 3.10.12 is installed in $HOME/.pyenv/versions/3.10.12 folder, then CMAKE_PREFIX_PATH should include this path.