I have not done this for perhaps a decade or more. But apparently, things are still the same on Ubuntu 18.04:
sudo apt-get install build-essential
cpan
make install
install Bundle::CPAN
install App::GnuplotUtils
Adding a new python version to Ubuntu 20.04 (the 3rd after 2.7 and 3.8):
sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.6 3
To change between python versions:
sudo update-alternatives --config python