The dplyr package introduced the %.% operator to pass the left hand side as an argument of the function on the right hand side, similar to a *NIX p
dplyr
%.%
See the very first item in the current NEWS file:
dplyr now imports %>% from magrittr (#330). I recommend that you use this instead of %.% because it is easier to type (since you can hold down the shift key) and is more flexible
%>%