QA: What formula syntax is used by the RevoScaleR analysis functions?

The formula syntax used by the RevoScaleR analysis functions is similar to regular R formula syntax. The most important difference between the two is that the RevoScaleR formulas have limited support for variable transformation. 

The recommended way to perform transformations is either to use the rxDataStepXdf() function for a priori transformations of the variables or by generating on the fly transformations using the 'transformFunc' and 'transformVars' arguments that are supported by most RevoScaleR functions. 
You can find more specific information in the 'rxFormula' help file(type 'help(rxFormula)'.