Python

Python is an interpreted general-purpose programming language.

Setup

You can install python using various ways. With pyenv you can switch between different versions. Install pyenv and pyenv-virtualenv and proceed with adding

export PATH=${HOME}/.pyenv/bin:$PATH
eval "$(pyenv init -)"
eval "$(pyenv virtualenv-init -)"

to your ~/.profile. You can then set and install your preferred version of python globally with pyenv install <version> and pyenv global <version>.

Analog to managing python versions, pipenv can manage pip and package versions. A guide and description of the usage can be found on gioele.io.

Manual Installation

This section is based on a guide by Linuxize.

On Linux-based systems Python can be easily installed using make. The following shows a process of installing Python 3.9.1. When another Python version is needed the version number has to be adapted accordingly.

First make sure all the dependencies are installed. On a Ubuntu system or other systems using the apt package manager this can look like the following

sudo apt update
sudo apt install build-essential zlib1g-dev libncurses5-dev libgdbm-dev libnss3-dev libssl-dev libreadline-dev libffi-dev libsqlite3-dev wget libbz2-dev

Afterwards the python source code can be downloaded.

wget https://www.python.org/ftp/python/3.9.1/Python-3.9.1.tgz
tar -xf Python-3.9.1.tgz
cd Python-3.9.1

Afterwards if OpenSSL should be enabled for Python uncomment all the corresponding lines in Modules/Setup. This part of the guide is taken from a StackOverflow post by Ironman.

Then proceed with the installation.

./configure --enable-optimizations
make
sudo make altinstall

Afterwards you can check if the Pyhton version is installed using the following command.

python3.9 --version

Usage

Create a requirements file

To automatically create a requirements.txt of your current project, navigate to it and run pipreqs (install it if not already done).

Modules

There are various modules and package managers to install these for python like pip. For this usually a virtual environment is needed - as it is described in the setup section. Alternatively local package manager like the ones of various Linux distributions can sometimes be used to install packages globally. Due to different package versions (especially on rolling release distributions) this can fail. If it doesnt work the packages can be installed globally using pip together with the --break-system-packages flag. This flag is to be used with care.

Pytorch

Setup Pytorch with Cuda for GPU usage

If you are on Arch Linux or a distribution based on it install python-pytorch-cuda via pacman -S python-pytorch-cuda.

After that visit the official pytorch website and install pytorch for your custom configuration.

After that try to run the following python script:

import torch

torch.cuda.is_available()

This should give back True.

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