Opc.Ua.Server.CountAggregateCalculator.ComputeNumberOfTransitions C# (CSharp) Method

        protected DataValue ComputeNumberOfTransitions(TimeSlice slice)
        {
            // get the values in the slice.
            List<DataValue> values = GetValues(slice);

            // check for empty slice.
            if (values == null)
            {
                return GetNoDataValue(slice);
            }

            // determine whether a transition occurs at the StartTime
            double lastValue = Double.NaN;

            if (slice.EarlyBound != null)
            {
                if (StatusCode.IsGood(slice.EarlyBound.Value.StatusCode))
                {
                    try
                    {
                        lastValue = CastToDouble(slice.EarlyBound.Value);
                    }
                    catch (Exception)
                    {
                        lastValue = Double.NaN;
                    }
                }
            }

            // count the transitions.
            int count = 0;

            for (int ii = 0; ii < values.Count; ii++)
            {
                if (!IsGood(values[ii]))
                {
                    continue;
                }

                double nextValue = 0;

                try
                {
                    nextValue = CastToDouble(values[ii]);
                }
                catch (Exception)
                {
                    continue;
                }

                if (!Double.IsNaN(lastValue))
                {
                    if (lastValue != nextValue)
                    {
                        count++;
                    }
                }

                lastValue = nextValue;
            }

            // set the timestamp and status.
            DataValue value = new DataValue();
            value.WrappedValue = new Variant(count, TypeInfo.Scalars.Int32);
            value.SourceTimestamp = GetTimestamp(slice);
            value.ServerTimestamp = GetTimestamp(slice);
            value.StatusCode = value.StatusCode.SetAggregateBits(AggregateBits.Calculated);
            value.StatusCode = GetValueBasedStatusCode(slice, values, value.StatusCode);

            // return result.
            return value;
        }
        #endregion