Remove never executed codes

src/Microsoft.Data.Analysis/GroupBy.cs

@@ -82,7 +82,7 @@ public GroupBy(DataFrame dataFrame, int groupByColumnIndex, IDictionary<TKey, IC
                 throw new ArgumentException(nameof(groupByColumnIndex));
             _groupByColumnIndex = groupByColumnIndex;
             _keyToRowIndicesMap = keyToRowIndices ?? throw new ArgumentException(nameof(keyToRowIndices));
-            _dataFrame = dataFrame ?? throw new ArgumentException(nameof(dataFrame));
+            _dataFrame = dataFrame;
         }
 
         private delegate void ColumnDelegate(int columnIndex, long rowIndex, ICollection<long> rows, TKey key, bool firstGroup);

src/Microsoft.Data.Analysis/StringDataFrameColumn.cs

@@ -374,7 +374,7 @@ private StringDataFrameColumn Clone(PrimitiveDataFrameColumn<long> mapIndices =
         {
             if (mapIndices is null)
             {
-                StringDataFrameColumn ret = new StringDataFrameColumn(Name, mapIndices is null ? Length : mapIndices.Length);
+                StringDataFrameColumn ret = new StringDataFrameColumn(Name, Length);
                 for (long i = 0; i < Length; i++)
                 {
                     ret[i] = this[i];

src/Microsoft.ML.Data/Scorers/BinaryClassifierScorer.cs

@@ -277,7 +277,7 @@ private void GetPredictedLabelCore(float score, ref bool value)
 
         private void GetPredictedLabelCoreAsKey(float score, ref uint value)
         {
-            value = (uint)(score > _threshold ? 2 : score <= _threshold ? 1 : 0);
+            value = (uint)(score > _threshold ? 2 : 1);
         }
 
         private protected override JToken PredictedLabelPfa(string[] mapperOutputs)

src/Microsoft.ML.Maml/MAML.cs

@@ -82,18 +82,8 @@ private static int MainWithProgress(string args)
 
         private static ConsoleEnvironment CreateEnvironment()
         {
-            string sensitivityString = null;
             MessageSensitivity sensitivity = MessageSensitivity.All;
-            if (!string.IsNullOrWhiteSpace(sensitivityString))
-            {
-                // Cannot use host or channels since the environment isn't even
-                // created yet.
-                if (!Enum.TryParse(sensitivityString, out sensitivity))
-                {
-                    Console.Error.WriteLine("Cannot parse '{0}' as {1}", sensitivityString, nameof(MessageSensitivity));
-                    sensitivity = MessageSensitivity.All;
-                }
-            }
+
             return new ConsoleEnvironment(sensitivity: sensitivity);
         }