Pyenv + Virtualenv + ROS Noetic

Pyenv

sudo apt update && sudo apt upgrade -y

Install dependencies

sudo apt install -y make build-essential libssl-dev zlib1g-dev\
libbz2-dev libreadline-dev libsqlite3-dev wget curl llvm libncurses5-dev\
libncursesw5-dev xz-utils tk-dev libffi-dev liblzma-dev python-openssl\
git

Clone Pyenv

git clone https://github.com/pyenv/pyenv.git ~/.pyenv

Set environment variables

echo 'export PYENV_ROOT="$HOME/.pyenv"' >> ~/.bashrc
echo 'export PATH="$PYENV_ROOT/bin:$PATH"' >> ~/.bashrc
echo 'eval "$(pyenv init --path)"' >> ~/.bashrc

exec "$SHELL"

Install the desired Python version

pyenv install 3.9.1

Other useful commands

pyenv install --list
pyenv versions

Pyenv Virtualenv Plugin

Clone Virtualenv Pyenv plugin

git clone https://github.com/pyenv/pyenv-virtualenv.git $(pyenv root)/plugins/pyenv-virtualenv

Set environment variables

echo 'eval "$(pyenv virtualenv-init -)"' >> ~/.bashrc
exec "$SHELL"

Create an enviroment named "ai" and set it as the global python interpreter

pyenv virtualenv 3.9.1 ai
pyenv global ai

Or only set to local in a folder

pyenv local ai

Or only activate and deactivate on demand

pyenv activate ai
pyenv deactivate

ROS Noetic

Add keys

sudo sh -c 'echo "deb http://packages.ros.org/ros/ubuntu $(lsb_release -sc) main" > /etc/apt/sources.list.d/ros-latest.list'
curl -s https://raw.githubusercontent.com/ros/rosdistro/master/ros.asc | sudo apt-key add -

Update and install ROS Noetic Desktop

sudo apt update
sudo apt install ros-noetic-desktop-full

Set environment variables

echo "source /opt/ros/noetic/setup.bash" >> ~/.bashrc
source ~/.bashrc

Install the ROS Python tools

pyenv activate ai
pip install rosdep rosinstall rosinstall-generator wstool catkin_tools empy

ROS Workspace

Create the workspace

mkdir -p ~/catkin_ws/src
cd ~/catkin_ws

Initialize the workspace

catkin init
catkin build

Source the setup.bash file (repeat after a build)

source devel/setup.bash

You can add that to .bashrc if you want (but you still have to call it after a build)

echo "source ~/catkin_ws/devel/setup.bash" >> ~/.bashrc

To build packages in release mode

cd ~/catkin_ws/
catkin config -DCMAKE_BUILD_TYPE=Release