Signature Description Parameters
templat<typename T, typename I = unsigned long, typename = typename std::enable_if<std::is_arithmetic<T>::value, T>::type>
struct KthValueVisitor;
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 finds the Kth element in the given column in linear time.
          explicit KthValueVisitor (size_type ke, bool skipnan = true);
        
T: Column data type
I: Index type