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Clean up graph code
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Leroy Korterink committed Oct 27, 2018
1 parent 7f31909 commit 43254f9
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Showing 4 changed files with 80 additions and 35 deletions.
4 changes: 2 additions & 2 deletions Graph/Edge.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,10 +2,10 @@ namespace Graph
{
public class Edge
{
public IVertex Destination;
public Vertex Destination;
public double Cost;

public Edge(IVertex destination, double cost)
public Edge(Vertex destination, double cost)
{
Destination = destination;
Cost = cost;
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66 changes: 52 additions & 14 deletions Graph/Graph.cs
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Original file line number Diff line number Diff line change
@@ -1,7 +1,6 @@
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http.Headers;
using PriorityQueue;

namespace Graph
Expand All @@ -18,7 +17,7 @@ public class Graph : IGraph
/// </summary>
/// <param name="vertexName"></param>
/// <returns></returns>
public IVertex GetVertex(string vertexName)
public Vertex GetVertex(string vertexName)
{
if (VertexMap.TryGetValue(vertexName, out var vertex)) return vertex;

Expand All @@ -28,9 +27,15 @@ public IVertex GetVertex(string vertexName)
return vertex;
}

/// <summary>
/// Adds a new edge to the current graph
/// </summary>
/// <param name="sourceVertexName"></param>
/// <param name="destinationVertexName"></param>
/// <param name="cost"></param>
public void AddEdge(string sourceVertexName, string destinationVertexName, double cost)
{
var sourceVertex = (Vertex) GetVertex(sourceVertexName);
var sourceVertex = GetVertex(sourceVertexName);
var destinationVertex = GetVertex(destinationVertexName);

sourceVertex.AdjacentVertices.Add(new Edge(destinationVertex, cost));
Expand Down Expand Up @@ -77,12 +82,6 @@ public string PathToString(string destinationName)
return $"(Cost is: {vertex.Distance}) {PathToString(vertex)}";
}


public override string ToString()
{
throw new NotImplementedException();
}

#region Shortest-path algorithms

/// <summary>
Expand All @@ -106,13 +105,13 @@ public void Unweighted(string startVertexName)
while (queue.Count != 0)
{
var currentVertex = queue.Dequeue();

// Set visited to true so we can check if the graph is connected or not
currentVertex.Visited = true;

currentVertex.AdjacentVertices.ForEach(edge =>
{
var adjacentVertex = (Vertex) edge.Destination;
var adjacentVertex = edge.Destination;

if (adjacentVertex.Distance != Infinity) return;

Expand All @@ -124,6 +123,12 @@ public void Unweighted(string startVertexName)
}
}

/// <summary>
/// Single-source weighted shortest-path algorithm
/// </summary>
/// <param name="startVertexName"></param>
/// <exception cref="NoSuchElementException"></exception>
/// <exception cref="GraphException"></exception>
public void Dijkstra(string startVertexName)
{
ClearAll();
Expand Down Expand Up @@ -151,7 +156,7 @@ public void Dijkstra(string startVertexName)

vertex.AdjacentVertices.ForEach(edge =>
{
var adjacentVertex = (Vertex) edge.Destination;
var adjacentVertex = edge.Destination;
var edgeCost = edge.Cost;

if (edgeCost < 0)
Expand All @@ -171,17 +176,50 @@ public void Dijkstra(string startVertexName)

#endregion

/// <summary>
/// Checks whether all vertices in this graph are connected
/// </summary>
/// <returns></returns>
public bool IsConnected()
{
Unweighted(VertexMap.First().Value.Name);
Unweighted(VertexMap.First().Value.Name);

foreach (var vertex in VertexMap.Values)
// Return false when any vertex has not been visited
if (!vertex.Visited)
return false;

return true;
}

/// <summary>
/// Prints vertex with its adjacent vertices
///
/// V0 --> V1(2) V3(1)
/// V1 --> V3(3) V4(10)
/// V2 --> V0(4) V5(5)
/// V3 --> V2(2) V5(8) V6(4) V4(2)
/// V4 --> V6(6)
/// V5 -->
/// V6 --> V5(1)
/// </summary>
/// <returns></returns>
public override string ToString()
{
var output = "";

foreach (var vertex in VertexMap.Values)
{
var adjacentVertexes = vertex.AdjacentVertices.Aggregate(
"",
(accumulator, edge) => { return accumulator += $"{edge.Destination.Name}({edge.Cost})"; }
);

output += vertex.Name + " --> " + adjacentVertexes;
}

return output;
}
}

#region Custom error classes
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2 changes: 1 addition & 1 deletion Graph/IGraph.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ namespace Graph
{
public interface IGraph
{
IVertex GetVertex(string vertexName);
Vertex GetVertex(string vertexName);

void AddEdge(string sourceVertexName, string destinationVertexName, double cost);

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43 changes: 25 additions & 18 deletions GraphTests/GraphTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -54,7 +54,7 @@ public void Should_GetVertex()
var myGraph = new Graph.Graph();
myGraph.AddEdge("V0", "V1", 5);

var myVertex = (Vertex) myGraph.GetVertex("V0");
var myVertex = myGraph.GetVertex("V0");

Assert.Equal("V0", myVertex.Name);
}
Expand All @@ -65,7 +65,7 @@ public void Should_AddEdge()
var myGraph = new Graph.Graph();
myGraph.AddEdge("V0", "V1", 5);

var myVertex = (Vertex) myGraph.GetVertex("V0");
var myVertex = myGraph.GetVertex("V0");

Assert.Equal(5, myVertex.AdjacentVertices[0].Cost);
}
Expand All @@ -88,13 +88,13 @@ public void Should_Unweighted()

myGraph.Unweighted("V0");

Assert.Equal(0, ((Vertex) myGraph.GetVertex("V0")).Distance);
Assert.Equal(1, ((Vertex) myGraph.GetVertex("V1")).Distance);
Assert.Equal(2, ((Vertex) myGraph.GetVertex("V2")).Distance);
Assert.Equal(1, ((Vertex) myGraph.GetVertex("V3")).Distance);
Assert.Equal(2, ((Vertex) myGraph.GetVertex("V4")).Distance);
Assert.Equal(2, ((Vertex) myGraph.GetVertex("V5")).Distance);
Assert.Equal(2, ((Vertex) myGraph.GetVertex("V6")).Distance);
Assert.Equal(0, (myGraph.GetVertex("V0")).Distance);
Assert.Equal(1, (myGraph.GetVertex("V1")).Distance);
Assert.Equal(2, (myGraph.GetVertex("V2")).Distance);
Assert.Equal(1, (myGraph.GetVertex("V3")).Distance);
Assert.Equal(2, (myGraph.GetVertex("V4")).Distance);
Assert.Equal(2, (myGraph.GetVertex("V5")).Distance);
Assert.Equal(2, (myGraph.GetVertex("V6")).Distance);
}

[Fact]
Expand All @@ -104,13 +104,13 @@ public void Should_Dijkstra()

myGraph.Dijkstra("V0");

Assert.Equal(0, ((Vertex) myGraph.GetVertex("V0")).Distance);
Assert.Equal(2, ((Vertex) myGraph.GetVertex("V1")).Distance);
Assert.Equal(3, ((Vertex) myGraph.GetVertex("V2")).Distance);
Assert.Equal(1, ((Vertex) myGraph.GetVertex("V3")).Distance);
Assert.Equal(3, ((Vertex) myGraph.GetVertex("V4")).Distance);
Assert.Equal(6, ((Vertex) myGraph.GetVertex("V5")).Distance);
Assert.Equal(5, ((Vertex) myGraph.GetVertex("V6")).Distance);
Assert.Equal(0, (myGraph.GetVertex("V0")).Distance);
Assert.Equal(2, (myGraph.GetVertex("V1")).Distance);
Assert.Equal(3, (myGraph.GetVertex("V2")).Distance);
Assert.Equal(1, (myGraph.GetVertex("V3")).Distance);
Assert.Equal(3, (myGraph.GetVertex("V4")).Distance);
Assert.Equal(6, (myGraph.GetVertex("V5")).Distance);
Assert.Equal(5, (myGraph.GetVertex("V6")).Distance);
}

[Fact]
Expand All @@ -120,12 +120,12 @@ public void Should_ReturnTrue_When_IsConnected()

Assert.True(myGraph.IsConnected());
}

[Fact]
public void Should_ReturnFalse_When_IsNotConnected()
{
var myGraph = new Graph.Graph();

myGraph.AddEdge("V0", "V1", 2);
myGraph.AddEdge("V2", "V3", 3);

Expand All @@ -137,7 +137,14 @@ public void Should_ToString()
{
var myGraph = CreateGraph();

myGraph.Dijkstra("V0");

_output.WriteLine(myGraph.ToString());

Assert.Equal(
"V0 --> V1(2) V3(1)\nV1 --> V3(3) V4(10)\nV2 --> V0(4) V5(5)\nV3 --> V2(2) V5(8) V6(4) V4(2)\nV4 --> V6(6)\nV5 -->\nV6 --> V5(1)\n",
myGraph.ToString()
);
}
}
}

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