Simplify initialize code

Author: JakeRadMSFT

src/Microsoft.Data.Analysis/NumberMathComputation.cs

@@ -169,6 +169,25 @@ protected void CumulativeApply(PrimitiveColumnContainer<T> column, Func<T, T, T>
             }
         }
 
+        protected T CalculateReduction(PrimitiveColumnContainer<T> column, Func<T, T, T> func, T startValue)
+        {
+            var ret = startValue;
+
+            for (int b = 0; b < column.Buffers.Count; b++)
+            {
+                var buffer = column.Buffers[b].ReadOnlySpan;
+                var bitMap = column.NullBitMapBuffers[b].ReadOnlySpan;
+                for (int i = 0; i < buffer.Length; i++)
+                {
+                    if (column.IsValid(bitMap, i))
+                    {
+                        ret = checked(func(ret, buffer[i]));
+                    }
+                }
+            }
+            return ret;
+        }
+
         protected void CumulativeApply(PrimitiveColumnContainer<T> column, Func<T, T, T> func, IEnumerable<long> rows)
         {
             T ret = T.Zero;
@@ -179,27 +198,7 @@ protected void CumulativeApply(PrimitiveColumnContainer<T> column, Func<T, T, T>
             long maxCapacity = maxRange;
             IEnumerator<long> enumerator = rows.GetEnumerator();
 
-            bool isValid = false;
-            while (!isValid && enumerator.MoveNext())
-            {
-                long row = enumerator.Current;
-                if (row < minRange || row >= maxRange)
-                {
-                    int bufferIndex = (int)(row / maxCapacity);
-                    buffer = column.Buffers.GetOrCreateMutable(bufferIndex).Span;
-                    bitmap = column.NullBitMapBuffers[bufferIndex].ReadOnlySpan;
-                    minRange = checked(bufferIndex * maxCapacity);
-                    maxRange = checked((bufferIndex + 1) * maxCapacity);
-                }
-
-                row -= minRange;
-                if (column.IsValid(bitmap, (int)row))
-                {
-                    isValid = true;
-                    ret = buffer[(int)row];
-                }
-            }
-
+            bool isInitialized = false;
             while (enumerator.MoveNext())
             {
                 long row = enumerator.Current;
@@ -215,30 +214,18 @@ protected void CumulativeApply(PrimitiveColumnContainer<T> column, Func<T, T, T>
                 row -= minRange;
                 if (column.IsValid(bitmap, (int)row))
                 {
-                    ret = func(ret, buffer[(int)row]);
-                    buffer[(int)row] = ret;
-                }
-            }
-        }
-
-
-        protected T CalculateReduction(PrimitiveColumnContainer<T> column, Func<T, T, T> func, T startValue)
-        {
-            var ret = startValue;
-
-            for (int b = 0; b < column.Buffers.Count; b++)
-            {
-                var buffer = column.Buffers[b].ReadOnlySpan;
-                var bitMap = column.NullBitMapBuffers[b].ReadOnlySpan;
-                for (int i = 0; i < buffer.Length; i++)
-                {
-                    if (column.IsValid(bitMap, i))
+                    if (!isInitialized)
                     {
-                        ret = checked(func(ret, buffer[i]));
+                        isInitialized = true;
+                        ret = buffer[(int)row];
+                    }
+                    else
+                    {
+                        ret = func(ret, buffer[(int)row]);
+                        buffer[(int)row] = ret;
                     }
                 }
             }
-            return ret;
         }
 
         protected T CalculateReduction(PrimitiveColumnContainer<T> column, Func<T, T, T> func, IEnumerable<long> rows)
@@ -251,27 +238,7 @@ protected T CalculateReduction(PrimitiveColumnContainer<T> column, Func<T, T, T>
             long maxCapacity = maxRange;
             IEnumerator<long> enumerator = rows.GetEnumerator();
 
-            bool isValid = false;
-            while (!isValid && enumerator.MoveNext())
-            {
-                long row = enumerator.Current;
-                if (row < minRange || row >= maxRange)
-                {
-                    int bufferIndex = (int)(row / maxCapacity);
-                    buffer = column.Buffers[bufferIndex].ReadOnlySpan;
-                    bitMap = column.NullBitMapBuffers[bufferIndex].ReadOnlySpan;
-                    minRange = checked(bufferIndex * maxCapacity);
-                    maxRange = checked((bufferIndex + 1) * maxCapacity);
-                }
-                row -= minRange;
-
-                if (column.IsValid(bitMap, (int)row))
-                {
-                    isValid = true;
-                    ret = buffer[(int)row];
-                }
-            }
-
+            bool isInitialized = false;
             while (enumerator.MoveNext())
             {
                 long row = enumerator.Current;
@@ -287,9 +254,16 @@ protected T CalculateReduction(PrimitiveColumnContainer<T> column, Func<T, T, T>
 
                 if (column.IsValid(bitMap, (int)row))
                 {
-                    ret = checked(func(ret, buffer[(int)row]));
+                    if (!isInitialized)
+                    {
+                        isInitialized = true;
+                        ret = buffer[(int)row];
+                    }
+                    else
+                    {
+                        ret = checked(func(ret, buffer[(int)row]));
+                    }
                 }
-
             }
 
             return ret;