R is a popular open-source environment for statistical analysis. Tableau Desktop can now connect to R through calculated fields and take advantage of R functions, libraries, packages and even saved models. These calculations dynamically invoke the R engine and pass values to R via the Rserve package, and are returned back to Tableau.
Tableau Server can also be configured to connect to an instance of Rserve through the tabadmin utility, allowing anyone to view a dashboard containing R functionality.
Combining R with Tableau gives you the ability to bring deep statistical analysis into a drag-and-drop visual analytics environment.
Note that only Tableau Desktop and Tableau Server 8.1 support R at this time.