[GitHub] [arrow] zixi-bwang commented on a change in pull request #12068: ARROW-15037: [C#] A stream processing example of IoT sensor data

[GitBox <gi...@apache.org>]

zixi-bwang commented on a change in pull request #12068:
URL: https://github.com/apache/arrow/pull/12068#discussion_r780739266



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File path: csharp/examples/IoTDataPipelineExample/Model/SensorDataPipeline.cs
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@@ -0,0 +1,225 @@
+// Licensed to the Apache Software Foundation (ASF) under one or more
+// contributor license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright ownership.
+// The ASF licenses this file to You under the Apache License, Version 2.0
+// (the "License"); you may not use this file except in compliance with
+// the License.  You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System;
+using System.IO;
+using System.Threading.Tasks;
+using System.Collections.Generic;
+using Apache.Arrow;
+using Apache.Arrow.Ipc;
+using Apache.Arrow.Memory;
+using System.Threading.Channels;
+using System.Threading;
+using Apache.Arrow.Types;
+
+namespace IoTPipelineExample
+{
+    public class SensorDataPipeline
+    {
+        private int _size;
+        private readonly int _totalInputs;
+        private readonly int _queueCapacity;
+        private readonly Channel<SensorData> _channel;
+        ChannelWriter<SensorData> _writer;
+        ChannelReader<SensorData> _reader;
+
+        private readonly Dictionary<int, Int32Array.Builder> _colSubjectIdBuilderDict;
+        private readonly Dictionary<int, StringArray.Builder> _colActivityLabelBuilderDict;
+        private readonly Dictionary<int, TimestampArray.Builder> _colTimestampBuilderDict;
+        private readonly Dictionary<int, DoubleArray.Builder> _colXAxisBuilderDict;
+        private readonly Dictionary<int, DoubleArray.Builder> _colYAxisBuilderDict;
+        private readonly Dictionary<int, DoubleArray.Builder> _colZAxisBuilderDict;
+
+        public Dictionary<string, string> activityLabel = new Dictionary<string, string>()
+            {
+                {"walking", "A"},
+                {"jogging", "B"},
+                {"stairs", "C"},
+                {"sitting", "D"},
+                {"standing", "E"},
+                {"typing", "F"},
+                {"teeth", "G"},
+                {"soup", "H"},
+                {"chips", "I"},
+                {"pasta", "J"},
+                {"drinking", "K"},
+                {"sandwich", "L"},
+                {"kicking", "M"},
+                {"catch", "O"},
+                {"dribbling", "P"},
+                {"writing", "Q"},
+                {"clapping", "R"},
+                {"folding", "S"},
+            };
+
+        public SensorDataPipeline(int totalInputs, int queueCapacity)
+        {
+            _totalInputs = totalInputs;
+            _queueCapacity = queueCapacity;
+            _channel = Channel.CreateBounded<SensorData>(_queueCapacity);
+            _writer = _channel.Writer;
+            _reader = _channel.Reader;
+            _colSubjectIdBuilderDict = new Dictionary<int, Int32Array.Builder>();
+            _colActivityLabelBuilderDict = new Dictionary<int, StringArray.Builder>();
+            _colTimestampBuilderDict = new Dictionary<int, TimestampArray.Builder>();
+            _colXAxisBuilderDict = new Dictionary<int, DoubleArray.Builder>();
+            _colYAxisBuilderDict = new Dictionary<int, DoubleArray.Builder>();
+            _colZAxisBuilderDict = new Dictionary<int, DoubleArray.Builder>();
+        }
+
+        public async Task WriteToChannel(int taskNumber)
+        {
+            Random rand = new Random();
+            List<string> keyList = new List<string>(activityLabel.Keys);
+            int count = keyList.Count;
+            var basis = DateTimeOffset.UtcNow;
+
+            Console.WriteLine($"Write to channel task {taskNumber} started!");
+            while (await _writer.WaitToWriteAsync())
+            {
+                string randomKey = keyList[rand.Next(count)];
+                string label = activityLabel[randomKey];
+
+                // generate random missing values
+                if (rand.Next(10_000) == 9_999)
+                {
+                    label = null;
+                }
+
+                var item = new SensorData
+                {
+                    // approximately 9_000 unique subjects/sensors
+                    subjectId = rand.Next(1_001, 1_123),

Review comment:
       You are right.




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