Signature Description Parameters
templat<typename T, typename I = unsigned long, typename = typename std::enable_if<std::is_arithmetic<T>::value, T>::type>
struct ReturnVisitor;
This is a “single action visitor”, meaning it is passed the whole data vector in one call and you must use the single_action_visit() interface.
This functor class calculates the return of a given column, according to the return policy (monetary, percentage, or log). The result is a vector of returns.
explicit ReturnVisitor (return_policy rp);
See this document and dataframe_tester.cc for examples.
T: Column data type.
I: Index type.