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Fix bug where FindWindowStartIndex did not correctly handle NaN-values (oxyplot#1512)
* Fix issue oxyplot#1512, Fix bug where FindWindowStartIndex did not correctly handle NaN-values * Set Minimum = 4
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‎CHANGELOG.md‎

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@@ -79,6 +79,7 @@ All notable changes to this project will be documented in this file.
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- Display of ampersands in OxyPlot.WindowsForms Tracker (#1585)
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- Full Plotarea Polar plot rendering with non-zero minimum values (#1586)
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- Auto margins are set incorrectly if Axis.TitleFontSize is set to non-default value (related to #1577)
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- Incomplete rendering of AreaSeries in some situations (#1512)
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## [2.0.0] - 2019-10-19
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### Added

‎CONTRIBUTORS‎

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# Please keep the list sorted.
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Alexei Shcherbakov
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Anders Musikka <anders@andersmusikka.se>
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Auriou
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Bartłomiej Szypelow <bszypelow@users.noreply.github.com>
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benjaminrupp

‎Source/Examples/ExampleLibrary/Issues/Issues.cs‎

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@@ -2283,6 +2283,38 @@ public static PlotModel EmojiText()
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return plot;
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}
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[Example("#1512: FindWindowStartIndex.")]
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public static PlotModel FindWindowsStartIndex()
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{
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var plotModel1 = new PlotModel { Title = "AreaSeries broken in time" };
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var axis = new LinearAxis {Position = AxisPosition.Left, MinimumPadding = 0, MaximumPadding = 0.06, AbsoluteMinimum = 0};
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var xAxis = new LinearAxis() {Position = AxisPosition.Bottom, Minimum = 4};
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plotModel1.Axes.Add(axis);
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plotModel1.Axes.Add(xAxis);
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var N = 15;
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var random = new Random(6);
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var currentValue = random.NextDouble() - 0.5;
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var areaSeries = new AreaSeries();
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for (int i = 0; i < N; ++i)
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{
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if (random.Next(4) == 0)
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{
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areaSeries.Points.Add(DataPoint.Undefined);
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areaSeries.Points2.Add(DataPoint.Undefined);
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}
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currentValue += random.NextDouble();
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areaSeries.Points.Add(new DataPoint(currentValue, currentValue));
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areaSeries.Points2.Add(new DataPoint(currentValue, currentValue));
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}
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plotModel1.Series.Add(areaSeries);
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return plotModel1;
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}
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private class TimeSpanPoint
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{

‎Source/OxyPlot.Tests/Axes/XYAxisSeriesTest.cs‎

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// --------------------------------------------------------------------------------------------------------------------
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// <copyright file="XYAxisSeriesTests.cs" company="OxyPlot">
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// Copyright (c) 2020 OxyPlot contributors
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// </copyright>
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// <summary>
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// Provides unit tests for the <see cref="XYAxisSeries" /> class.
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// </summary>
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// --------------------------------------------------------------------------------------------------------------------
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namespace OxyPlot.Tests
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{
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using System;
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using NUnit.Framework;
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using OxyPlot.Series;
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/// <summary>
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/// Provides unit tests for the <see cref="XYAxisSeries" /> class.
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/// </summary>
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public class XYAxisSeriesTests
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{
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/// <summary>
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/// Test class just to allow methods in XYAxisSeries to be tested.
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/// </summary>
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private class TestAxisSeries : XYAxisSeries
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{
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public override void Render(IRenderContext rc)
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{
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throw new NotImplementedException();
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}
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}
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/// <summary>
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/// Generate lots of random data, then checking the FindWindowStartIndex method
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/// against this data.
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/// </summary>
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[Test]
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public void RunFuzzTest()
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{
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for (int i = 0; i < 10000; ++i)
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{
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FuzzIteration(i);
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}
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}
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/// <summary>
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/// Generate lots of random data, then checking the FindWindowStartIndex method
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/// against this data. This time with data containing NaN-values.
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/// </summary>
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[Test]
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public void RunFuzzWithNanTest()
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{
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for (int i = 0; i < 10000; ++i)
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{
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FuzzIterationWithNan(i);
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}
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}
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private static void FuzzIteration(int seed)
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{
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var xyAxiseries = new TestAxisSeries();
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var N = 15;
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var random = new Random(seed);
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var testData = new System.Collections.Generic.List<double>();
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var currentValue = random.NextDouble() - 0.5;
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for (int i = 0; i < N; ++i)
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{
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testData.Add(currentValue);
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currentValue += random.NextDouble();
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}
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var targetX = random.NextDouble() * (N / 2.0) - 1.0;
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var guess = random.Next(0, testData.Count);
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int foundIndex = xyAxiseries.FindWindowStartIndex(testData, x => x, targetX, guess);
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if (foundIndex > 0)
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Assert.LessOrEqual(testData[foundIndex], targetX, "At " + seed);
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if (foundIndex < testData.Count - 1)
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Assert.GreaterOrEqual(testData[foundIndex + 1], targetX, "At " + seed);
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}
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private static void FuzzIterationWithNan(int seed)
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{
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var xyAxiseries = new TestAxisSeries();
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var N = 15;
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var random = new Random(seed);
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var testData = new System.Collections.Generic.List<double>();
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var currentValue = random.NextDouble() - 0.5;
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for (int i = 0; i < N; ++i)
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{
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if (random.Next(4) == 0)
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testData.Add(double.NaN);
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testData.Add(currentValue);
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currentValue += random.NextDouble();
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}
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double? PrevNonNan(int index)
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{
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while (index >= 0)
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{
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if (double.IsNaN(testData[index]) == false)
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return testData[index];
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index -= 1;
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}
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return null;
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}
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double? NextNonNan(int index)
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{
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while (index >= 0)
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{
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if (double.IsNaN(testData[index]) == false)
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return testData[index];
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index += 1;
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}
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return null;
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}
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var targetX = random.NextDouble() * (N / 2.0) - 1.0;
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var guess = random.Next(0, testData.Count);
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int foundIndex = xyAxiseries.FindWindowStartIndex(testData, x => x, targetX, guess);
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if (foundIndex > 0)
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{
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if (double.IsNaN(testData[foundIndex]))
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{
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var prevNonNaN = PrevNonNan(foundIndex-1);
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if (prevNonNaN.HasValue)
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Assert.LessOrEqual(prevNonNaN, targetX, "At " + seed);
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}
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else
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{
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Assert.LessOrEqual(testData[foundIndex], targetX, "At " + seed);
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}
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}
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if (foundIndex < testData.Count - 1)
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{
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if (double.IsNaN(testData[foundIndex + 1]))
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{
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var nextNonNaN = NextNonNan(foundIndex+1);
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if (nextNonNaN.HasValue)
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Assert.GreaterOrEqual(nextNonNaN, targetX, "At " + seed);
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}
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else
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{
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Assert.GreaterOrEqual(testData[foundIndex + 1], targetX, "At " + seed);
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}
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}
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}
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}
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}

‎Source/OxyPlot/Series/XYAxisSeries.cs‎

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@@ -750,62 +750,65 @@ protected int UpdateWindowStartIndex<T>(IList<T> items, Func<T, double> xgetter,
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/// <param name="targetX">target x.</param>
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/// <param name="initialGuess">initial guess index.</param>
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/// <returns>
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/// index of x with max(x) &lt;= target x or -1 if cannot find
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/// index of x with max(x) &lt;= target x or 0 if cannot find
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/// </returns>
755-
protected int FindWindowStartIndex<T>(IList<T> items, Func<T, double> xgetter, double targetX, int initialGuess)
755+
public int FindWindowStartIndex<T>(IList<T> items, Func<T, double> xgetter, double targetX, int initialGuess)
756756
{
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int lastguess = 0;
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int start = 0;
759-
int end = items.Count - 1;
760-
int curGuess = initialGuess;
758+
int nominalEnd = items.Count - 1;
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while (nominalEnd > 0 && double.IsNaN(xgetter(items[nominalEnd])))
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nominalEnd -= 1;
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int end = nominalEnd;
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int curGuess = Math.Max(0, Math.Min(end, initialGuess));
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762-
while (start <= end)
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double GetX(int index)
763765
{
764-
if (curGuess < start)
766+
while (index <= nominalEnd)
765767
{
766-
return lastguess;
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}
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else if (curGuess > end)
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{
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return end;
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double guessX = xgetter(items[index]);
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if (double.IsNaN(guessX))
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index += 1;
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else
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return guessX;
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}
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return xgetter(items[nominalEnd]);
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}
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773-
double guessX = xgetter(items[curGuess]);
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while (start < end)
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{
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double guessX = GetX(curGuess);
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if (guessX.Equals(targetX))
775781
{
776-
return curGuess;
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start = curGuess;
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break;
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}
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else if (guessX > targetX)
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{
780787
end = curGuess - 1;
781-
if (end < start)
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{
783-
return lastguess;
784-
}
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else if (end == start)
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{
787-
return end;
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}
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}
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else
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{
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start = curGuess + 1;
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lastguess = curGuess;
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{
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start = curGuess;
794792
}
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796794
if (start >= end)
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{
798-
return lastguess;
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break;
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}
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801-
double endX = xgetter(items[end]);
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double startX = xgetter(items[start]);
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double endX = GetX(end);
800+
double startX = GetX(start);
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804802
var m = (end - start + 1) / (endX - startX);
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805804
curGuess = start + (int)((targetX - startX) * m);
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curGuess = Math.Max(start + 1, Math.Min(curGuess, end));
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}
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808-
return lastguess;
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while (start > 0 && (xgetter(items[start]) > targetX))
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start -= 1;
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return start;
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}
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}
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}

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