Initial commit

srcs/RobotNet10/RobotApp/Communication/CartographerSharp/Common/FixedRatioSampler.cs

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+/*
+ * Copyright 2016 The Cartographer Authors
+ *
+ * Licensed 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.
+ */
+
+namespace CartographerSharp.Common;
+
+/// <summary>
+/// Signals when a sample should be taken from a stream of data to select a
+/// uniformly distributed fraction of the data.
+/// </summary>
+public class FixedRatioSampler
+{
+    /// <summary>
+    /// Sampling occurs if the proportion of samples to pulses drops below this number.
+    /// </summary>
+    private readonly double _ratio;
+
+    private long _numPulses = 0;
+    private long _numSamples = 0;
+
+    /// <summary>
+    /// Creates a fixed ratio sampler with the given ratio.
+    /// </summary>
+    /// <param name="ratio">Ratio between 0.0 and 1.0. Sampling occurs if the proportion of samples to pulses drops below this number.</param>
+    public FixedRatioSampler(double ratio)
+    {
+        if (ratio < 0.0 || ratio > 1.0)
+        {
+            throw new ArgumentException($"Ratio must be between 0.0 and 1.0, got {ratio}", nameof(ratio));
+        }
+        
+        if (ratio == 0.0)
+        {
+            // Warning: FixedRatioSampler is dropping all data
+        }
+        
+        _ratio = ratio;
+    }
+
+    /// <summary>
+    /// Returns true if this pulse should result in a sample.
+    /// </summary>
+    public bool Pulse()
+    {
+        _numPulses++;
+        if (_numSamples / _numPulses < _ratio)
+        {
+            _numSamples++;
+            return true;
+        }
+        return false;
+    }
+
+    /// <summary>
+    /// Returns a debug string describing the current ratio of samples to pulses.
+    /// </summary>
+    public string DebugString()
+    {
+        var percentage = _numPulses > 0 ? 100.0 * _numSamples / _numPulses : 0.0;
+        return $"{_numSamples} ({percentage:F2}%)";
+    }
+}