├── README.md ├── Sources ├── CSharpIDW │ ├── CSharpIDW.csproj │ ├── InterpolationResult.cs │ ├── Point.cs │ ├── CSharpIDW.nuspec │ └── IdwInterpolator.cs ├── CSharpIDW.Test │ ├── CSharpIDW.Test.csproj │ └── IdwInterpolatorTests.cs └── CSharpIDW.sln ├── LICENSE └── .gitignore /README.md: -------------------------------------------------------------------------------- 1 | [![Build status](https://ci.appveyor.com/api/projects/status/tbtl3f2s8qfgoymj?svg=true)](https://ci.appveyor.com/project/argonavis80/csharp-idw) 2 | 3 | # CSharp-IDW 4 | C# library for fast multi-dimensional inverse distance weighting (IDW) interpolation. 5 | -------------------------------------------------------------------------------- /Sources/CSharpIDW/CSharpIDW.csproj: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | netcoreapp3.1 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | -------------------------------------------------------------------------------- /Sources/CSharpIDW/InterpolationResult.cs: -------------------------------------------------------------------------------- 1 | namespace CSharpIDW 2 | { 3 | public class InterpolationResult 4 | { 5 | public enum ResultOptions 6 | { 7 | Hit, 8 | NearestNeighbor, 9 | Interpolated, 10 | Extrapolated, 11 | OutOfBounds 12 | } 13 | 14 | public ResultOptions Result { get; set; } 15 | 16 | public double Value { get; set; } 17 | 18 | public Point? Point { get; set; } 19 | } 20 | } -------------------------------------------------------------------------------- /Sources/CSharpIDW/Point.cs: -------------------------------------------------------------------------------- 1 | using System.Globalization; 2 | using System.Linq; 3 | 4 | namespace CSharpIDW 5 | { 6 | public struct Point 7 | { 8 | public double Value { get; } 9 | 10 | public double[] Coordinates { get; } 11 | 12 | public Point(double value, params double[] coordinates) 13 | { 14 | Value = value; 15 | Coordinates = coordinates; 16 | } 17 | 18 | public override string ToString() 19 | { 20 | return $"{string.Join(";", Coordinates)} -> {Value}"; 21 | } 22 | } 23 | } -------------------------------------------------------------------------------- /Sources/CSharpIDW.Test/CSharpIDW.Test.csproj: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | netcoreapp3.1 5 | 6 | 7 | 8 | 9 | 10 | 11 | all 12 | runtime; build; native; contentfiles; analyzers; buildtransitive 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | -------------------------------------------------------------------------------- /Sources/CSharpIDW/CSharpIDW.nuspec: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | $id$ 5 | $version$ 6 | $title$ 7 | $author$ 8 | $author$ 9 | https://github.com/argonavis80/CSharp-IDW/blob/master/LICENSE 10 | https://github.com/argonavis80/CSharp-IDW 11 | 12 | false 13 | $description$ 14 | 15 | Copyright 2016 16 | Interpolation IDW Scatter 17 | 18 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | MIT License 2 | 3 | Copyright (c) 2016 Henrik Alfke 4 | 5 | Permission is hereby granted, free of charge, to any person obtaining a copy 6 | of this software and associated documentation files (the "Software"), to deal 7 | in the Software without restriction, including without limitation the rights 8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 9 | copies of the Software, and to permit persons to whom the Software is 10 | furnished to do so, subject to the following conditions: 11 | 12 | The above copyright notice and this permission notice shall be included in all 13 | copies or substantial portions of the Software. 14 | 15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 21 | SOFTWARE. 22 | 23 | 24 | 25 | Credits 26 | --------------------------- 27 | This application uses Open Source components. You can find the source code of 28 | their open source projects along with license information below. We acknowledge 29 | and are grateful to these developers for their contributions to open source. 30 | 31 | Project: KdTree 32 | Copyright (c) 2013 codeandcats 33 | License (MIT): https://github.com/codeandcats/KdTree/blob/master/LICENSE -------------------------------------------------------------------------------- /Sources/CSharpIDW.sln: -------------------------------------------------------------------------------- 1 | 2 | Microsoft Visual Studio Solution File, Format Version 12.00 3 | # Visual Studio Version 16 4 | VisualStudioVersion = 16.0.30711.63 5 | MinimumVisualStudioVersion = 10.0.40219.1 6 | Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Tests", "Tests", "{95954717-385E-4527-80BF-6E376ACD36F0}" 7 | EndProject 8 | Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "CSharpIDW", "CSharpIDW\CSharpIDW.csproj", "{8789D37F-0F8E-4E89-BF29-4F14B9FF6FF0}" 9 | EndProject 10 | Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "CSharpIDW.Test", "CSharpIDW.Test\CSharpIDW.Test.csproj", "{97727039-E72C-45A8-9AF5-5873F687A7FF}" 11 | EndProject 12 | Global 13 | GlobalSection(SolutionConfigurationPlatforms) = preSolution 14 | Debug|Any CPU = Debug|Any CPU 15 | Release|Any CPU = Release|Any CPU 16 | EndGlobalSection 17 | GlobalSection(ProjectConfigurationPlatforms) = postSolution 18 | {8789D37F-0F8E-4E89-BF29-4F14B9FF6FF0}.Debug|Any CPU.ActiveCfg = Debug|Any CPU 19 | {8789D37F-0F8E-4E89-BF29-4F14B9FF6FF0}.Debug|Any CPU.Build.0 = Debug|Any CPU 20 | {8789D37F-0F8E-4E89-BF29-4F14B9FF6FF0}.Release|Any CPU.ActiveCfg = Release|Any CPU 21 | {8789D37F-0F8E-4E89-BF29-4F14B9FF6FF0}.Release|Any CPU.Build.0 = Release|Any CPU 22 | {97727039-E72C-45A8-9AF5-5873F687A7FF}.Debug|Any CPU.ActiveCfg = Debug|Any CPU 23 | {97727039-E72C-45A8-9AF5-5873F687A7FF}.Debug|Any CPU.Build.0 = Debug|Any CPU 24 | {97727039-E72C-45A8-9AF5-5873F687A7FF}.Release|Any CPU.ActiveCfg = Release|Any CPU 25 | {97727039-E72C-45A8-9AF5-5873F687A7FF}.Release|Any CPU.Build.0 = Release|Any CPU 26 | EndGlobalSection 27 | GlobalSection(SolutionProperties) = preSolution 28 | HideSolutionNode = FALSE 29 | EndGlobalSection 30 | GlobalSection(NestedProjects) = preSolution 31 | {97727039-E72C-45A8-9AF5-5873F687A7FF} = {95954717-385E-4527-80BF-6E376ACD36F0} 32 | EndGlobalSection 33 | GlobalSection(ExtensibilityGlobals) = postSolution 34 | SolutionGuid = {6A509FB9-7625-4283-9E2F-AAA18AC56F8C} 35 | EndGlobalSection 36 | EndGlobal 37 | -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | ## Ignore Visual Studio temporary files, build results, and 2 | ## files generated by popular Visual Studio add-ons. 3 | 4 | # User-specific files 5 | *.suo 6 | *.user 7 | *.userosscache 8 | *.sln.docstates 9 | 10 | # User-specific files (MonoDevelop/Xamarin Studio) 11 | *.userprefs 12 | 13 | # Build results 14 | [Dd]ebug/ 15 | [Dd]ebugPublic/ 16 | [Rr]elease/ 17 | [Rr]eleases/ 18 | x64/ 19 | x86/ 20 | bld/ 21 | [Bb]in/ 22 | [Oo]bj/ 23 | [Ll]og/ 24 | 25 | # Visual Studio 2015 cache/options directory 26 | .vs/ 27 | # Uncomment if you have tasks that create the project's static files in wwwroot 28 | #wwwroot/ 29 | 30 | # MSTest test Results 31 | [Tt]est[Rr]esult*/ 32 | [Bb]uild[Ll]og.* 33 | 34 | # NUNIT 35 | *.VisualState.xml 36 | TestResult.xml 37 | 38 | # Build Results of an ATL Project 39 | [Dd]ebugPS/ 40 | [Rr]eleasePS/ 41 | dlldata.c 42 | 43 | # DNX 44 | project.lock.json 45 | artifacts/ 46 | 47 | *_i.c 48 | *_p.c 49 | *_i.h 50 | *.ilk 51 | *.meta 52 | *.obj 53 | *.pch 54 | *.pdb 55 | *.pgc 56 | *.pgd 57 | *.rsp 58 | *.sbr 59 | *.tlb 60 | *.tli 61 | *.tlh 62 | *.tmp 63 | *.tmp_proj 64 | *.log 65 | *.vspscc 66 | *.vssscc 67 | .builds 68 | *.pidb 69 | *.svclog 70 | *.scc 71 | 72 | # Chutzpah Test files 73 | _Chutzpah* 74 | 75 | # Visual C++ cache files 76 | ipch/ 77 | *.aps 78 | *.ncb 79 | *.opendb 80 | *.opensdf 81 | *.sdf 82 | *.cachefile 83 | *.VC.db 84 | *.VC.VC.opendb 85 | 86 | # Visual Studio profiler 87 | *.psess 88 | *.vsp 89 | *.vspx 90 | *.sap 91 | 92 | # TFS 2012 Local Workspace 93 | $tf/ 94 | 95 | # Guidance Automation Toolkit 96 | *.gpState 97 | 98 | # ReSharper is a .NET coding add-in 99 | _ReSharper*/ 100 | *.[Rr]e[Ss]harper 101 | *.DotSettings.user 102 | 103 | # JustCode is a .NET coding add-in 104 | .JustCode 105 | 106 | # TeamCity is a build add-in 107 | _TeamCity* 108 | 109 | # DotCover is a Code Coverage Tool 110 | *.dotCover 111 | 112 | # NCrunch 113 | _NCrunch_* 114 | .*crunch*.local.xml 115 | nCrunchTemp_* 116 | 117 | # MightyMoose 118 | *.mm.* 119 | AutoTest.Net/ 120 | 121 | # Web workbench (sass) 122 | .sass-cache/ 123 | 124 | # Installshield output folder 125 | [Ee]xpress/ 126 | 127 | # DocProject is a documentation generator add-in 128 | DocProject/buildhelp/ 129 | DocProject/Help/*.HxT 130 | DocProject/Help/*.HxC 131 | DocProject/Help/*.hhc 132 | DocProject/Help/*.hhk 133 | DocProject/Help/*.hhp 134 | DocProject/Help/Html2 135 | DocProject/Help/html 136 | 137 | # Click-Once directory 138 | publish/ 139 | 140 | # Publish Web Output 141 | *.[Pp]ublish.xml 142 | *.azurePubxml 143 | # TODO: Comment the next line if you want to checkin your web deploy settings 144 | # but database connection strings (with potential passwords) will be unencrypted 145 | *.pubxml 146 | *.publishproj 147 | 148 | # Microsoft Azure Web App publish settings. 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Backup files are not needed, 205 | # because we have git ;-) 206 | _UpgradeReport_Files/ 207 | Backup*/ 208 | UpgradeLog*.XML 209 | UpgradeLog*.htm 210 | 211 | # SQL Server files 212 | *.mdf 213 | *.ldf 214 | 215 | # Business Intelligence projects 216 | *.rdl.data 217 | *.bim.layout 218 | *.bim_*.settings 219 | 220 | # Microsoft Fakes 221 | FakesAssemblies/ 222 | 223 | # GhostDoc plugin setting file 224 | *.GhostDoc.xml 225 | 226 | # Node.js Tools for Visual Studio 227 | .ntvs_analysis.dat 228 | 229 | # Visual Studio 6 build log 230 | *.plg 231 | 232 | # Visual Studio 6 workspace options file 233 | *.opt 234 | 235 | # Visual Studio LightSwitch build output 236 | **/*.HTMLClient/GeneratedArtifacts 237 | **/*.DesktopClient/GeneratedArtifacts 238 | **/*.DesktopClient/ModelManifest.xml 239 | **/*.Server/GeneratedArtifacts 240 | **/*.Server/ModelManifest.xml 241 | _Pvt_Extensions 242 | 243 | # Paket dependency manager 244 | .paket/paket.exe 245 | paket-files/ 246 | 247 | # FAKE - F# Make 248 | .fake/ 249 | 250 | # JetBrains Rider 251 | .idea/ 252 | *.sln.iml 253 | -------------------------------------------------------------------------------- /Sources/CSharpIDW.Test/IdwInterpolatorTests.cs: -------------------------------------------------------------------------------- 1 | using System; 2 | using System.Collections.Generic; 3 | using System.Diagnostics.CodeAnalysis; 4 | using System.Linq; 5 | using Xunit; 6 | // ReSharper disable ArgumentsStyleLiteral 7 | // ReSharper disable PossibleInvalidOperationException 8 | 9 | namespace CSharpIDW.Test 10 | { 11 | [ExcludeFromCodeCoverage] 12 | public class IdwInterpolatorTests 13 | { 14 | private List _pointRange; 15 | 16 | public IdwInterpolatorTests() 17 | { 18 | _pointRange = new List 19 | { 20 | new Point(1.0, 0, 0), 21 | new Point(1.1, 0, 1), 22 | new Point(1.2, 0, 2), 23 | new Point(2.0, 1, 0), 24 | new Point(2.2, 1, 1), 25 | new Point(2.4, 1, 2), 26 | new Point(3.0, 2, 0), 27 | new Point(3.3, 2, 1), 28 | new Point(3.6, 2, 2), 29 | }; 30 | } 31 | 32 | [Fact] 33 | public void FailDimensionOutOfRange() 34 | { 35 | // ReSharper disable once UnusedVariable 36 | Assert.Throws(() => new IdwInterpolator(dimensions: 0)); 37 | } 38 | 39 | [Fact] 40 | public void FailPowerOutOfRange() 41 | { 42 | // ReSharper disable once UnusedVariable 43 | Assert.Throws(() => new IdwInterpolator(dimensions: 2, power: 0)); 44 | } 45 | 46 | [Fact] 47 | public void FailNumberOfNeighboursOutOfRange() 48 | { 49 | // ReSharper disable once UnusedVariable 50 | Assert.Throws(() => new IdwInterpolator(dimensions: 2, power: 2, numberOfNeighbours: 0)); 51 | } 52 | 53 | [Fact] 54 | public void FailWithTooFewPoints() 55 | { 56 | var target = new IdwInterpolator(dimensions: 2, power: 2, numberOfNeighbours: 5); 57 | 58 | target.AddPointRange(_pointRange.Take(4).ToList()); // Not enough points. 59 | 60 | Assert.Throws(() => target.Interpolate(1, 1)); 61 | } 62 | 63 | [Fact] 64 | public void FailWithNullPointRange() 65 | { 66 | var target = new IdwInterpolator(dimensions: 2, power: 2, numberOfNeighbours: 5); 67 | 68 | Assert.Throws(() => target.AddPointRange(null)); 69 | } 70 | 71 | [Fact] 72 | public void FailWithPointWithWrongDimension() 73 | { 74 | var target = new IdwInterpolator(dimensions: 2, power: 2, numberOfNeighbours: 5); 75 | 76 | Assert.Throws(() => target.AddPoint(new Point(1, 1, 1, 1))); // One dimension too much. 77 | } 78 | 79 | [Fact] 80 | public void FailWithPointAndMissingCoordinates() 81 | { 82 | var target = new IdwInterpolator(dimensions: 2, power: 2, numberOfNeighbours: 5); 83 | 84 | Assert.Throws(() => target.AddPoint(1, null)); // Coordinates missing. 85 | } 86 | 87 | [Fact] 88 | public void FailWithPointAndCoordinatesWithWrongDimension() 89 | { 90 | var target = new IdwInterpolator(dimensions: 2, power: 2, numberOfNeighbours: 5); 91 | 92 | Assert.Throws(() => target.AddPoint(1, 1, 1, 1)); // One dimension too much. 93 | } 94 | 95 | [Fact] 96 | public void FailWithPointRangeWithWrongDimension() 97 | { 98 | var target = new IdwInterpolator(dimensions: 2, power: 2, numberOfNeighbours: 5); 99 | 100 | var pointRange = new List 101 | { 102 | new Point(1.0, 0, 0), 103 | new Point(1.1, 0, 1), 104 | new Point(1.2, 0, 2), 105 | new Point(2.0, 1, 0), 106 | new Point(2.2, 1, 1), 107 | new Point(2.4, 1) // Dimension wrong. 108 | }; 109 | 110 | Assert.Throws(() => target.AddPointRange(pointRange)); 111 | } 112 | 113 | [Fact] 114 | public void FailInterpolateWithWrongDimension() 115 | { 116 | var target = new IdwInterpolator(dimensions: 2, power: 2, numberOfNeighbours: 5); 117 | 118 | target.AddPointRange(_pointRange); 119 | 120 | Assert.Throws(() => target.Interpolate(1, 1, 1)); // One dimension to much. 121 | } 122 | 123 | [Fact] 124 | public void TestInterpolateWithPointHit() 125 | { 126 | var target = new IdwInterpolator(dimensions: 2, power: 2, numberOfNeighbours: 4); 127 | 128 | target.AddPointRange(_pointRange); // Test adding point range. 129 | 130 | var result = target.Interpolate(1, 1); 131 | 132 | Assert.Equal(2.2, result.Value); 133 | Assert.Equal(1, result.Point.Value.Coordinates[0]); 134 | Assert.Equal(1, result.Point.Value.Coordinates[1]); 135 | Assert.Equal(InterpolationResult.ResultOptions.Hit, result.Result); 136 | } 137 | 138 | [Fact] 139 | public void TestNearestNeighbourInterpolation() 140 | { 141 | var target = new IdwInterpolator(dimensions: 2, power: 2, numberOfNeighbours: 1); 142 | 143 | foreach (var point in _pointRange) 144 | { 145 | target.AddPoint(point); // Test adding points. 146 | } 147 | 148 | var result = target.Interpolate(1.1, 1.1); 149 | 150 | Assert.Equal(2.2, result.Value); 151 | Assert.Equal(1, result.Point.Value.Coordinates[0]); 152 | Assert.Equal(1, result.Point.Value.Coordinates[1]); 153 | Assert.Equal(InterpolationResult.ResultOptions.NearestNeighbor, result.Result); 154 | } 155 | 156 | 157 | 158 | [Fact] 159 | public void TestWeightedInterpolation() 160 | { 161 | var target = new IdwInterpolator(dimensions: 2, power: 2, numberOfNeighbours: 4); 162 | 163 | foreach (var point in _pointRange) 164 | { 165 | target.AddPoint(point.Value, point.Coordinates); // Test adding bare values. 166 | } 167 | 168 | var result = target.Interpolate(1.5, 1.5); 169 | 170 | Assert.Equal(2.875, result.Value, 3); 171 | Assert.Equal(InterpolationResult.ResultOptions.Interpolated, result.Result); 172 | Assert.Null(result.Point); 173 | } 174 | 175 | //[Fact] 176 | //public void TestWeightedExtrapolation() 177 | //{ 178 | // // TODO: Currently failing, because convex hull not yet checked. 179 | 180 | // var target = new IdwInterpolator(dimensions: 2, power: 2, numberOfNeighbours: 4); 181 | 182 | // target.AddPointRange(_pointRange); 183 | 184 | // var result = target.Interpolate(2.1, 2.1); 185 | 186 | // Assert.AreEqual(2.2, result.Value); 187 | // Assert.AreEqual(InterpolationResult.ResultOptions.Extrapolated, result.Result); 188 | // Assert.IsNull(result.Point); 189 | //} 190 | } 191 | } 192 | -------------------------------------------------------------------------------- /Sources/CSharpIDW/IdwInterpolator.cs: -------------------------------------------------------------------------------- 1 | using System; 2 | using System.Collections.Generic; 3 | using System.Linq; 4 | using KdTree; 5 | using KdTree.Math; 6 | // ReSharper disable SuggestBaseTypeForParameter 7 | 8 | namespace CSharpIDW 9 | { 10 | /// 11 | /// Inverse Distance Weighting (IDW) interpolator. 12 | /// 13 | /// 14 | /// The interpolator implements the modified Shepard's method, with only nearest neighbours. 15 | /// https://en.wikipedia.org/wiki/Inverse_distance_weighting 16 | /// 17 | public class IdwInterpolator 18 | { 19 | private readonly int _dimensions; 20 | 21 | private const double DefaultPower = 2; 22 | private const int DefaultNumberOfNeighbours = 5; 23 | 24 | private readonly KdTree _tree; 25 | 26 | private double Power { get; } 27 | 28 | private int NumberOfNeighbours { get; } 29 | 30 | public IdwInterpolator(int dimensions) : this(dimensions, DefaultPower) 31 | { 32 | } 33 | 34 | public IdwInterpolator(int dimensions, double power) : this(dimensions, power, DefaultNumberOfNeighbours) 35 | { 36 | } 37 | 38 | public IdwInterpolator(int dimensions, double power, int numberOfNeighbours) 39 | { 40 | if (dimensions < 1) 41 | throw new ArgumentOutOfRangeException(nameof(dimensions), dimensions, 42 | $"Parameter '{nameof(dimensions)}' must be a positive integer."); 43 | 44 | if (power <= 0) 45 | throw new ArgumentOutOfRangeException(nameof(power), power, 46 | $"Parameter '{nameof(power)}' must be a positive real value."); 47 | 48 | if (numberOfNeighbours < 1) 49 | throw new ArgumentOutOfRangeException(nameof(numberOfNeighbours), numberOfNeighbours, 50 | $"Parameter '{nameof(numberOfNeighbours)}' must be a positive integer."); 51 | 52 | _dimensions = dimensions; 53 | 54 | Power = power; 55 | NumberOfNeighbours = numberOfNeighbours; 56 | 57 | _tree = new KdTree(dimensions, new DoubleMath()); 58 | } 59 | 60 | public void AddPoint(double value, params double[] coordinates) 61 | { 62 | if (coordinates == null) 63 | throw new ArgumentNullException(nameof(coordinates)); 64 | 65 | if (coordinates.Length != _dimensions) 66 | throw new ArgumentException(nameof(coordinates), 67 | $"Size of {nameof(coordinates)} must match the dimension of the interpolator."); 68 | 69 | var point = new Point(value, coordinates); 70 | 71 | _tree.Add(coordinates, point); 72 | } 73 | 74 | public void AddPoint(Point point) 75 | { 76 | if (point.Coordinates.Length != _dimensions) 77 | throw new ArgumentException(nameof(point.Coordinates), 78 | $"Size of {nameof(point.Coordinates)} must match the dimension of the interpolator."); 79 | 80 | _tree.Add(point.Coordinates, point); 81 | } 82 | 83 | public void AddPointRange(IEnumerable points) 84 | { 85 | if (points == null) 86 | throw new ArgumentNullException(nameof(points)); 87 | 88 | foreach (var point in points) 89 | { 90 | if (point.Coordinates.Length != _dimensions) 91 | { 92 | _tree.Clear(); 93 | 94 | throw new ArgumentException(nameof(points), 95 | $"Size of coordinates of all items in {nameof(points)} must match the dimension of the interpolator."); 96 | } 97 | 98 | _tree.Add(point.Coordinates, point); 99 | } 100 | } 101 | 102 | public InterpolationResult Interpolate(params double[] coordinates) 103 | { 104 | if (coordinates.Length != _dimensions) 105 | throw new ArgumentException(nameof(coordinates), 106 | $"Size of {nameof(coordinates)} must match the dimension of the interpolator."); 107 | 108 | if (_tree.Count < NumberOfNeighbours) 109 | { 110 | throw new IndexOutOfRangeException( 111 | $"The number of found points ({_tree.Count}) is less than " + 112 | $"the number of required neighbours ({NumberOfNeighbours}). Consider reducing " + 113 | $"the required number of Neighbours with '{nameof(NumberOfNeighbours)}' property."); 114 | } 115 | 116 | Point point; 117 | 118 | if (_tree.TryFindValueAt(coordinates, out point)) 119 | { 120 | return new InterpolationResult 121 | { 122 | Point = point, 123 | Value = point.Value, 124 | Result = InterpolationResult.ResultOptions.Hit 125 | }; 126 | } 127 | 128 | var neighbours = _tree.GetNearestNeighbours(coordinates, NumberOfNeighbours); 129 | 130 | if (neighbours.Length == 1) 131 | { 132 | point = neighbours[0].Value; 133 | 134 | return new InterpolationResult 135 | { 136 | Point = point, 137 | Value = point.Value, 138 | Result = InterpolationResult.ResultOptions.NearestNeighbor 139 | }; 140 | } 141 | 142 | var value = CalculateWeightedAverage(neighbours.Select(n => n.Value), coordinates); 143 | 144 | var result = new InterpolationResult 145 | { 146 | Value = value, 147 | Result = InterpolationResult.ResultOptions.Interpolated 148 | }; 149 | 150 | if (false) // TODO: Check convex hull here. 151 | { 152 | result.Result = InterpolationResult.ResultOptions.Extrapolated; 153 | } 154 | 155 | return result; 156 | } 157 | 158 | private double CalculateWeightedAverage(IEnumerable points, double[] target) 159 | { 160 | var nominator = 0.0; 161 | var denominator = 0.0; 162 | 163 | foreach (var point in points) 164 | { 165 | var distance = CalculateDistance(point.Coordinates, target); 166 | var weight = 1/Math.Pow(distance, Power); 167 | 168 | nominator += weight*point.Value; 169 | denominator += weight; 170 | } 171 | 172 | var result = nominator/denominator; 173 | 174 | return result; 175 | } 176 | 177 | private static double CalculateDistance(double[] pointA, double[] pointB) 178 | { 179 | var sum = 0.0; 180 | 181 | for (var i = 0; i < pointA.Length; i++) 182 | { 183 | var p = pointA[i]; 184 | var q = pointB[i]; 185 | 186 | sum += Math.Pow(p - q, 2); 187 | } 188 | 189 | var result = Math.Sqrt(sum); 190 | 191 | return result; 192 | } 193 | } 194 | } 195 | --------------------------------------------------------------------------------