A few of weeks ago we had the release of Oracle R Enterprise (ORE).
There has been some posts on the R/ORE on the Oracle discussion forums about installing ORE on Oracle 12c.
It turns out that the only way to install ORE on an Oracle 12c database is if you do a traditional install. What this means is that you do not have a CDB and PDBs configuration of Oracle 12c.
I'll assume that Oracle are currently working on this particular issue, as you can imagine that that there is considerable amount of complexity in getting ORE to work with the PDBs.
If you are not using Oracle 12c then you are OK, as long as you are using 18.104.22.168 or 22.214.171.124 versions of the database. If you are using a lower version of the 11.2 database then you need to apply a patch to allow ORE to run.
As they say I'm sure it will be "fixed in the next release" :-)