Class DoubleSumOperator

    • Method Detail

      • getShortDescription

        public java.lang.String getShortDescription()
        Description copied from interface: IMultisetAggregationOperator
        A textual description of the operator.
      • getName

        public java.lang.String getName()
        Description copied from interface: IMultisetAggregationOperator
        A name or identifier of the operator.
      • createNeutral

        public java.lang.Double createNeutral()
        Returns:
        the neutral element, i.e. the interim result of aggregating an empty multiset.
      • isNeutral

        public boolean isNeutral​(java.lang.Double result)
        Returns:
        true if the interim result is equivalent to the neutral element, as if there are no values in the multiset. Must return true if the multiset is empty.
      • update

        public java.lang.Double update​(java.lang.Double oldResult,
                                       java.lang.Double updateValue,
                                       boolean isInsertion)
        Returns:
        an updated intermediate result, changed to reflect that a given object was added to / removed from the multiset (as indicated by the parameter isInsertion)
      • aggregateStream

        public java.lang.Double aggregateStream​(java.util.stream.Stream<java.lang.Double> stream)
        Description copied from interface: IMultisetAggregationOperator
        Calculates the aggregate results from a given stream of values; all values are considered as inserted
        Returns:
        the aggregate result, or null if no result can be calculated (e.g. because of an empty stream)
        Since:
        2.0