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Common/DTS.Common.Utilities/.svn/pristine/a1/a13506451b1967b71c691009c8f58e9f4bbba46b.svn-base

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+/*
+ * AverageShortValueOverTime.cs
+ *
+ * Copyright © 2009
+ * Diversified Technical Systems, Inc.
+ * All Rights Reserved
+ */
+
+using DTS.Common.Utilities.Logging;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace DTS.Common.Utilities
+{
+    /// <summary>
+    /// A class to represent the average value of a set of shorts over time.
+    /// </summary>
+    public class AverageShortValueOverTime
+        : AverageValueOverTime<short>
+    {
+        /// <summary>
+        /// Initialize an instance of the AverageShortValueOverTime class, assuming that no
+        /// averaging has been done yet.
+        /// </summary>
+        /// <param name="initialTime">
+        /// The <see cref="double"/> begin time of the average (using the time units specified
+        /// by the "TimeUnitSymbol" property.
+        /// </param>
+        /// 
+        /// <param name="sampleRate">
+        /// The <see cref="double"/> sample rate of the items being averaged (using the time units
+        /// specifed by the "TimeUnitSymbol" property.
+        /// </param>
+        /// 
+        /// <param name="timeUnitSymbol">
+        /// The <see cref="string"/> time unit description for begin/end times and the sample rate.
+        /// </param>
+        /// 
+        public AverageShortValueOverTime(double initialTime,
+                                          double sampleRate,
+                                          string timeUnitSymbol)
+            : base(initialTime,
+                    sampleRate,
+                    0,
+                    timeUnitSymbol)
+        {
+        }
+
+        /// <summary>
+        /// Initialize an instance of the AverageShortValueOverTime class.
+        /// </summary>
+        /// 
+        /// <param name="beginTime">
+        /// The <see cref="double"/> begin time of the average (using the time units specified
+        /// by the "TimeUnitSymbol" property.
+        /// </param>
+        /// 
+        /// <param name="endTime">
+        /// The <see cref="double"/> end time of the average (using the time units specified
+        /// by the "TimeUnitSymbol" property.
+        /// </param>
+        /// 
+        /// <param name="sampleRate">
+        /// The <see cref="double"/> sample rate of the items being averaged (using the time units
+        /// specifed by the "TimeUnitSymbol" property.
+        /// </param>
+        /// 
+        /// <param name="initialAverage">
+        /// The <see cref="short"/> pre-existing average to be appended to.
+        /// </param>
+        /// 
+        /// <param name="timeUnitSymbol">
+        /// The <see cref="string"/> time unit description for begin/end times and the sample rate.
+        /// </param>
+        /// 
+        public AverageShortValueOverTime(double beginTime,
+                                          double endTime,
+                                          double sampleRate,
+                                          short initialAverage,
+                                          string timeUnitSymbol)
+            : base(beginTime,
+                    endTime,
+                    sampleRate,
+                    initialAverage,
+                    timeUnitSymbol)
+        {
+        }
+
+        /// <summary>
+        /// Append the specified <see cref="T:List"/> of values to the running average.
+        /// </summary>
+        /// 
+        /// <param name="values">
+        /// The <see cref="T:List"/> of <see cref="short"/>s to be appended to the running average.
+        /// </param>
+        /// 
+        public override void AppendValues(List<short> values)
+        {
+            AppendValues(values.ToArray());
+        }
+
+        /// <summary>
+        /// Append the specified array of values to the running average.
+        /// </summary>
+        /// 
+        /// <param name="values">
+        /// The array of <see cref="short"/>s to be appended to the running average.
+        /// </param>
+        /// 
+        public override void AppendValues(short[] values)
+        {
+            if (0 == values.Length)
+            {
+                APILogger.Log($"AverageShortValueOverTime.AppendValues - no values to append");
+                return;
+            }
+            //
+            // Get the average of the appended values by themselves.
+            //
+            var numAppendixSamples = values.Length;
+            var appendixSamples = new double[numAppendixSamples];
+            for (var i = 0; i < numAppendixSamples; i++)
+                appendixSamples[i] = values[i];
+            var appendixAverage = appendixSamples.Average();
+
+            //
+            // Get the previous average and number of samples.
+            //
+            var numPreviousSamples = (ulong)((EndTime - BeginTime) * SampleRate);
+            double previousAverage = CurrentAverage;
+
+            //
+            // Now combine them with the previous average values (with the
+            // appropriate weighting) to get a new combined average.
+            //
+            var numTotalSamples = numPreviousSamples + (ulong)numAppendixSamples;
+            var combinedAverage = ((previousAverage * numPreviousSamples) + (appendixAverage * numAppendixSamples)) / numTotalSamples;
+
+            // Save our new average.
+            CurrentAverage = (short)combinedAverage;
+
+            // Update the end time to take into account the appended data.
+            EndTime += (numAppendixSamples / SampleRate);
+        }
+    }
+}