public void GenerateRandomGraph_GeneratesAcyclcGraph()
{
var settings = new RandomGraphSettings();
var graph = GraphHelper.GenerateRandomGraph(settings);
Assert.AreEqual(false, GraphHelper.HasCycles(graph));
}
private static void SetNodesLayers(List <Node> graph, RandomGraphSettings settings)
{
var startNode = graph.GetRandomElement();
startNode.Layer = 0;
var nonStartNodes = graph.Except(new[] { startNode }).ToList();
foreach (var node in nonStartNodes)
{
node.Layer = Random.Next(1, settings.LayerCount);
}
BalanceLayers(graph, settings);
}
public void GenerateRandomGraph_GeneratesChainIfNodeCountEqualsLayerCount()
{
var settings = new RandomGraphSettings
{
NodeCount = 10,
LayerCount = 10
};
var graph = GraphHelper.GenerateRandomGraph(settings);
var orderedGraph = graph.OrderBy(n => n.Layer).ToList();
for (var i = 0; i < settings.NodeCount; ++i)
{
Assert.AreEqual(i, orderedGraph[i].Layer);
}
}
public void GenerateRandomGraph_GeneratesGraphsWithCorrectParams()
{
var settings = new RandomGraphSettings
{
NodeCount = 10,
LayerCount = 4,
MaxNodeDegree = 5,
MinNodeDegree = 2
};
var graph = GraphHelper.GenerateRandomGraph(settings);
var distinctLayersCount = graph.GetLayerCount();
var minNodeDegree = graph.Where(n => n.Layer < distinctLayersCount - 1).Min(n => n.Degree);
Assert.AreEqual(settings.LayerCount, distinctLayersCount);
Assert.IsTrue(minNodeDegree >= settings.MinNodeDegree);
}
private static void BalanceLayers(IReadOnlyCollection <Node> graph, RandomGraphSettings settings)
{
var emptyLayers = Enumerable
.Range(1, settings.LayerCount - 1)
.Where(layer => graph.All(n => n.Layer != layer))
.ToList();
foreach (var emptyLayer in emptyLayers)
{
var largeLayers = Enumerable
.Range(1, settings.LayerCount - 1)
.Where(layer => graph.Count(n => n.Layer == layer) > 1)
.ToList();
var donorLayer = largeLayers.GetRandomElement();
graph.First(n => n.Layer == donorLayer).Layer = emptyLayer;
}
}
private static void AdjustHeights(List <Node> nodes, RandomGraphSettings settings) => nodes.ForEach(n => n.Height += n.NextNodes.Count * settings.DegreeHeightBonus);
public static List <Node> GenerateRandomGraph(RandomGraphSettings settings)
{
var graph = new List <Node>();
for (var i = 0; i < settings.NodeCount; ++i)
{
graph.Add(new Node
{
Height = NextDouble(settings.MinNodeHeight, settings.MaxNodeHeight),
Width = NextDouble(settings.MinNodeWidth, settings.MaxNodeWidth),
});
}
SetNodesLayers(graph, settings);
PrintDebugInfo(graph);
for (var i = 0; i < settings.LayerCount - 1; ++i)
{
var layer = graph.Where(n => n.Layer == i).ToList();
var nextLayer = graph.Where(n => n.Layer == i + 1).ToList();
var prevLayers = graph.Where(n => n.Layer <= i && n.Layer > 0).ToList();
foreach (var node in layer)
{
var nextNodeCount = Math.Max(Random.Next(settings.MinNodeDegree, settings.MaxNodeDegree + 1), nextLayer.Count);
var nextLayerNodes = prevLayers.Any() ? Random.Next(1, nextNodeCount + 1) : nextNodeCount;
for (var j = 0; j < nextLayerNodes; ++j)
{
node.NextNodes.Add(nextLayer.GetRandomElement());
}
var prevNodes = nextNodeCount - nextLayerNodes;
var prevNodesConnected = 0;
var attempts = 0;
while (prevNodesConnected < prevNodes && attempts < 10 * prevNodes)
{
var prevNode = prevLayers.GetRandomElement();
if (TryAddBackConnection(node, prevNode, graph))
{
prevNodesConnected++;
}
attempts++;
}
for (var j = 0; j < prevNodes - prevNodesConnected; ++j)
{
node.NextNodes.Add(nextLayer.GetRandomElement());
}
}
}
EnsureGraphIsConnected(graph);
PrintDebugInfo(graph);
SetPreviousNodes(graph);
AdjustHeights(graph, settings);
LayerHelper.SetLayers(graph);
LayerHelper.SetCoLayers(graph);
PrintDebugInfo(graph);
return(graph);
}
