Hash Aggregate C++ Sequence Methods

The Hash Aggregate C++ Sequence methods take various input arguments and return two iterators: result for the grouping values and groups for the group aggregates.

void hashAggMax(Sequence<T>& result, GenericSequence& groups, GenericSequence const& groupBy) const	Returns a sequence of the same type with the maximum value for each group of elements
void hashAggMin(Sequence<T>& result, GenericSequence& groups, GenericSequence const& groupBy) const	Returns a sequence of the same type with the minimum value for each group of elements
void hashAggSum(Sequence<R>& result, GenericSequence& groups, GenericSequence const& groupBy) const	Returns a sequence of the same type with the sum of each group of elements
void hashAggAvg(Sequence<double>& result, GenericSequence& groups, GenericSequence const& groupBy) const	Returns a double result sequence with the average of each group of elements
void hashAggApproxDistinctCount(Sequence<uint4>& result, GenericSequence& groups, GenericSequence const& groupBy) const	Returns a uint4 result sequence with the approximate district count for each group of elements
void hashAggCount(Sequence<uint8>& result, GenericSequence& groups) const	Returns a uint8 result sequence with the count of the number of elements in each group
void hashAggDistinctCount(Sequence<uint8>& result, GenericSequence& groups, GenericSequence const& groupBy) const	Returns a uint8 result_count sequence with the count of the number of distinct elements in each group
void hashAggDupCount(Sequence<uint8>& result, GenericSequence& groups, GenericSequence const& groupBy, mco_size_t minOccurrences) const	Returns a uint8 sequence with the count of duplicates in each group. Parameter minOccurrences specifies minimum number for occurrences of a particular value to be counted. With minOccurrences=1 this method is equivalent to hashAggDistinctCount(), with minOccurrences=2 it counts items encountered more than once.

Example

Following is an example code snippet demonstrating use of a hash aggregate method to calculate the average Close price for Volume values in ranges of 0..9, 10..19, 20..29, etc.:

    {
        mco_trans_h trans;
        mco_cursor_t quote_cursor;
        Quote quote;
        mco_seq_iterator_t close_iterator, volume_div_10_iterator; 
        mco_seq_iterator_t group_iterator,  avg_iterator;
        MCO_RET rc;
        ...
         
        for (rc = mco_cursor_first(trans, &quote_cursor); 
            rc != MCO_S_CURSOR_END; 
            rc = mco_cursor_next(trans, &quote_cursor)) 
        {
            Sequence<double> result;
            Sequence<uint4> groups;
             
            Quote_from_cursor(trans, &quote_cursor, &quote);
             
            quote.close_iterator().hashAggAvg(result, groups, quote.volume_iterator() / Sequence<uint4>(10));
            print_sequence(quote, result);
        }
        ...
    }