Add example for fixed penalty lateness for a vrptw
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Owen Lacey
169
examples/contrib/vrptw_fixed_penalty.cs
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169
examples/contrib/vrptw_fixed_penalty.cs
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// Copyright 2021 Owen Lacey
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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using System;
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using Google.OrTools.ConstraintSolver;
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/// <summary>
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/// Vehicles Routing Problem (VRP) with Time Windows, with the difference that we'll add a fixed penalty for lateness, as opposed to a linear penalty based on how late it is.
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/// Example is inspired by scheduling items which have contractual deadlines.
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/// Code based on https://developers.google.com/optimization/routing/vrptw#program
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/// </summary>
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public class VrpTimeWindowFixedPenalty
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{
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class DataModel
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{
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public long[,] TimeMatrix = {
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{ 0, 6, 9, 8, 7, 3, 6, 2, 3, 2, 6, 6, 4, 4, 5, 9, 7 },
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{ 6, 0, 8, 3, 2, 6, 8, 4, 8, 8, 13, 7, 5, 8, 12, 10, 14 },
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{ 9, 8, 0, 11, 10, 6, 3, 9, 5, 8, 4, 15, 14, 13, 9, 18, 9 },
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{ 8, 3, 11, 0, 1, 7, 10, 6, 10, 10, 14, 6, 7, 9, 14, 6, 16 },
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{ 7, 2, 10, 1, 0, 6, 9, 4, 8, 9, 13, 4, 6, 8, 12, 8, 14 },
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{ 3, 6, 6, 7, 6, 0, 2, 3, 2, 2, 7, 9, 7, 7, 6, 12, 8 },
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{ 6, 8, 3, 10, 9, 2, 0, 6, 2, 5, 4, 12, 10, 10, 6, 15, 5 },
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{ 2, 4, 9, 6, 4, 3, 6, 0, 4, 4, 8, 5, 4, 3, 7, 8, 10 },
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{ 3, 8, 5, 10, 8, 2, 2, 4, 0, 3, 4, 9, 8, 7, 3, 13, 6 },
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{ 2, 8, 8, 10, 9, 2, 5, 4, 3, 0, 4, 6, 5, 4, 3, 9, 5 },
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{ 6, 13, 4, 14, 13, 7, 4, 8, 4, 4, 0, 10, 9, 8, 4, 13, 4 },
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{ 6, 7, 15, 6, 4, 9, 12, 5, 9, 6, 10, 0, 1, 3, 7, 3, 10 },
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{ 4, 5, 14, 7, 6, 7, 10, 4, 8, 5, 9, 1, 0, 2, 6, 4, 8 },
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{ 4, 8, 13, 9, 8, 7, 10, 3, 7, 4, 8, 3, 2, 0, 4, 5, 6 },
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{ 5, 12, 9, 14, 12, 6, 6, 7, 3, 3, 4, 7, 6, 4, 0, 9, 2 },
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{ 9, 10, 18, 6, 8, 12, 15, 8, 13, 9, 13, 3, 4, 5, 9, 0, 9 },
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{ 7, 14, 9, 16, 14, 8, 5, 10, 6, 5, 4, 10, 8, 6, 2, 9, 0 },
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};
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public long[,] TimeWindows = {
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{ 0, 5 }, // depot
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{ 7, 12 }, // 1
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{ 10, 15 }, // 2
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{ 16, 18 }, // 3
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{ 10, 13 }, // 4
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{ 0, 5 }, // 5
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{ 5, 10 }, // 6
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{ 0, 4 }, // 7
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{ 5, 10 }, // 8
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{ 0, 3 }, // 9
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{ 10, 16 }, // 10
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{ 10, 15 }, // 11
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{ 0, 5 }, // 12
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{ 5, 10 }, // 13
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{ 7, 8 }, // 14
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{ 10, 15 }, // 15
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{ 11, 15 }, // 16
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};
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public int VehicleNumber = 4;
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public int Depot = 0;
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};
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/// <summary>
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/// Print the solution.
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/// </summary>
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static void PrintSolution(in DataModel data, in RoutingModel routing, in RoutingIndexManager manager,
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in Assignment solution)
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{
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RoutingDimension timeDimension = routing.GetMutableDimension("Time");
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// Inspect solution.
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long totalTime = 0;
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for (int i = 0; i < data.VehicleNumber; ++i)
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{
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Console.WriteLine("Route for Vehicle {0}:", i);
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var index = routing.Start(i);
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while (routing.IsEnd(index) == false)
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{
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var timeVar = timeDimension.CumulVar(index);
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Console.Write("{0} Time({1},{2}) -> ", manager.IndexToNode(index), solution.Min(timeVar),
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solution.Max(timeVar));
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index = solution.Value(routing.NextVar(index));
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}
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var endTimeVar = timeDimension.CumulVar(index);
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Console.WriteLine("{0} Time({1},{2})", manager.IndexToNode(index), solution.Min(endTimeVar),
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solution.Max(endTimeVar));
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Console.WriteLine("Time of the route: {0}min", solution.Min(endTimeVar));
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totalTime += solution.Min(endTimeVar);
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}
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Console.WriteLine("Total time of all routes: {0}min", totalTime);
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}
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public static void Main(String[] args)
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{
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// Instantiate the data problem.
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DataModel data = new DataModel();
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// Create Routing Index Manager
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RoutingIndexManager manager =
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new RoutingIndexManager(data.TimeMatrix.GetLength(0), data.VehicleNumber, data.Depot);
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// Create Routing Model.
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RoutingModel routing = new RoutingModel(manager);
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// Create and register a transit callback.
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int transitCallbackIndex = routing.RegisterTransitCallback((long fromIndex, long toIndex) =>
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{
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// Convert from routing variable Index to distance matrix NodeIndex.
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var fromNode = manager.IndexToNode(fromIndex);
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var toNode = manager.IndexToNode(toIndex);
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return data.TimeMatrix[fromNode, toNode];
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});
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// Define cost of each arc.
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routing.SetArcCostEvaluatorOfAllVehicles(transitCallbackIndex);
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// Add Distance constraint.
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routing.AddDimension(transitCallbackIndex, // transit callback
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30, // allow waiting time
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30, // vehicle maximum capacities
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false, // start cumul to zero
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"Time");
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RoutingDimension timeDimension = routing.GetMutableDimension("Time");
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routing.AddConstantDimensionWithSlack(0, // transit var 0 for all
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data.TimeMatrix.GetLength(0), // max value is every item being late
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1, // slack is 0 or 1 based on lateness
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true, // start cumul to zero
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"Late");
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RoutingDimension lateDimension = routing.GetMutableDimension("Late");
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// Add time window constraints for each location except depot.
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for (int i = 1; i < data.TimeWindows.GetLength(0); ++i)
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{
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long index = manager.NodeToIndex(i);
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var isLate = timeDimension.CumulVar(index) > data.TimeWindows[i, 1];
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// set the slack var to 1 if late
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routing.solver().MakeEquality(isLate, lateDimension.SlackVar(index));
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}
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// Instantiate route start and end times to produce feasible times.
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for (int i = 0; i < data.VehicleNumber; ++i)
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{
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// add a fixed penalty for each late item
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long penalty = 1000;
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lateDimension.SetCumulVarSoftUpperBound(routing.End(0), 0, penalty);
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routing.AddVariableMinimizedByFinalizer(lateDimension.CumulVar(routing.End(i)));
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}
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// Setting first solution heuristic.
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RoutingSearchParameters searchParameters =
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operations_research_constraint_solver.DefaultRoutingSearchParameters();
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searchParameters.FirstSolutionStrategy = FirstSolutionStrategy.Types.Value.PathCheapestArc;
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// Solve the problem.
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Assignment solution = routing.SolveWithParameters(searchParameters);
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// Print solution on console.
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PrintSolution(data, routing, manager, solution);
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}
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}
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23
examples/contrib/vrptw_fixed_penalty.csproj
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23
examples/contrib/vrptw_fixed_penalty.csproj
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@@ -0,0 +1,23 @@
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<Project Sdk="Microsoft.NET.Sdk">
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<PropertyGroup>
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<OutputType>Exe</OutputType>
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<LangVersion>7.3</LangVersion>
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<TargetFramework>netcoreapp2.1</TargetFramework>
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<EnableDefaultItems>false</EnableDefaultItems>
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<!-- see https://github.com/dotnet/docs/issues/12237 -->
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<RollForward>LatestMajor</RollForward>
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<AssemblyName>Google.OrTools.vrptw_fixed_penalty</AssemblyName>
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<IsPackable>true</IsPackable>
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</PropertyGroup>
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<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
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<DebugType>full</DebugType>
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<Optimize>true</Optimize>
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<GenerateTailCalls>true</GenerateTailCalls>
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</PropertyGroup>
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<ItemGroup>
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<Compile Include="vrptw_fixed_penalty.cs" />
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<PackageReference Include="Google.OrTools" Version="8.1.*" />
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</ItemGroup>
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</Project>
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