Update R Version

Recently, I updated from R 3.4 to R 3.6 following the description in

https://stackoverflow.com/questions/46214061/how-to-upgrade-r-in-linux

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys E298A3A825C0D65DFD57CBB651716619E084DAB9
sudo echo "deb http://cran.wustl.edu/bin/linux/ubuntu xenial/" | sudo tee -a /etc/apt/sources.list
sudo apt update
sudo apt upgrade r-base r-base-dev
sudo apt update
sudo apt upgrade

But with some minor additions from https://stackoverflow.com/questions/51256462/r-cannot-install-rjava-what-is-r-api-3-4

sudo add-apt-repository ppa:marutter/c2d4u3.5
sudo apt-get update 

and ...

sudo aptitude full-upgrade