public void SimpleAcyclic_A1()
{
// Simple acyclic graph.
var connList = new LightweightList <DirectedConnection>
{
new DirectedConnection(0, 3),
new DirectedConnection(1, 3),
new DirectedConnection(2, 3),
new DirectedConnection(2, 4),
new DirectedConnection(4, 3)
};
// Create graph.
var connSpan = connList.AsSpan();
connSpan.Sort();
var digraph = DirectedGraphBuilder.Create(connSpan, 3, 2);
// Perform depth analysis.
GraphDepthInfo depthInfo = new CyclicGraphDepthAnalysis().CalculateNodeDepths(digraph);
// Assertions.
Assert.Equal(3, depthInfo._graphDepth);
Assert.Equal(5, depthInfo._nodeDepthArr.Length);
// Node depths.
Assert.Equal(0, depthInfo._nodeDepthArr[0]);
Assert.Equal(0, depthInfo._nodeDepthArr[1]);
Assert.Equal(0, depthInfo._nodeDepthArr[2]);
Assert.Equal(2, depthInfo._nodeDepthArr[3]);
Assert.Equal(1, depthInfo._nodeDepthArr[4]);
}
/// <summary>
/// Create an array that gives the node layer for each node, keyed by node index.
/// </summary>
/// <param name="digraph">The directed cyclic graph.</param>
/// <returns>A new integer array.</returns>
private static int[] BuildNodeLayerByIdx_Cyclic(DirectedGraph digraph)
{
// Perform an analysis on the cyclic graph to assign a depth to each node.
// TODO: Re-use these instances, by maintaining a pool of them that can be 'rented from' and 'returned to' the pool.
CyclicGraphDepthAnalysis cyclicDepthAnalysis = new CyclicGraphDepthAnalysis();
GraphDepthInfo depthInfo = cyclicDepthAnalysis.CalculateNodeDepths(digraph);
int[] nodeLayerByIdx = depthInfo._nodeDepthArr;
// Move all nodes up one layer, such that layer 1 is the first/top layer; layer zero will be
// used later to represent input nodes only.
for (int i = digraph.InputCount; i < nodeLayerByIdx.Length; i++)
{
nodeLayerByIdx[i]++;
}
// Assign input nodes to their own layer (layer zero).
for (int i = 0; i < digraph.InputCount; i++)
{
nodeLayerByIdx[i] = 0;
}
// Assign output nodes to their own layer.
int outputLayerIdx = depthInfo._graphDepth + 1;
for (int i = 0; i < digraph.OutputCount; i++)
{
// Note. For cyclic networks the output node indexes occur in a contiguous segment following the input nodes.
int outputNodeIdx = digraph.InputCount + i;
nodeLayerByIdx[outputNodeIdx] = outputLayerIdx;
}
// Remove empty layers (if any), by adjusting the depth values in nodeLayerByIdx.
RemoveEmptyLayers(nodeLayerByIdx, outputLayerIdx + 1);
// Return the constructed node layer lookup table.
return(nodeLayerByIdx);
}
