/// <summary>
/// Create a directed graph based on the provided connections (between node IDs) and a predefined set of input/output
/// node IDs defined as being in a contiguous sequence starting at ID zero.
/// </summary>
/// <remarks>
/// connectionList is required to be sorted by sourceID, TargetID.
/// </remarks>
public static DirectedGraph Create(
IList <DirectedConnection> connectionList,
int inputCount, int outputCount)
{
// Debug assert that the connections are sorted.
Debug.Assert(SortUtils.IsSortedAscending(connectionList));
// Determine the full set of hidden node IDs.
int inputOutputCount = inputCount + outputCount;
var hiddenNodeIdArr = GetHiddenNodeIdArray(connectionList, inputOutputCount);
// Compile a mapping from current nodeIDs to new IDs (i.e. removing gaps in the ID space).
INodeIdMap nodeIdMap = DirectedGraphBuilderUtils.CompileNodeIdMap(
inputOutputCount, hiddenNodeIdArr);
// Extract/copy the neat genome connectivity graph into an array of DirectedConnection.
// Notes.
// The array contents will be manipulated, so copying this avoids modification of the genome's
// connection gene list.
// The IDs are substituted for node indexes here.
ConnectionIdArrays connIdArrays = CopyAndMapIds(connectionList, nodeIdMap);
// Construct and return a new DirectedGraph.
int totalNodeCount = inputOutputCount + hiddenNodeIdArr.Length;
return(new DirectedGraph(inputCount, outputCount, totalNodeCount, connIdArrays));
}
/// <summary>
/// Split each IWeightedDirectedConnection in a list into an array of DirectedConnections(s), and an array of weights.
/// Map the node IDs to indexes as we go.
/// </summary>
private static void CopyAndMapIds(
IList <WeightedDirectedConnection <T> > connectionList,
INodeIdMap nodeIdMap,
out ConnectionIdArrays connIdArrays,
out T[] weightArr)
{
int count = connectionList.Count;
int[] srcIdArr = new int[count];
int[] tgtIdArr = new int[count];
weightArr = new T[count];
for (int i = 0; i < count; i++)
{
srcIdArr[i] = nodeIdMap.Map(connectionList[i].SourceId);
tgtIdArr[i] = nodeIdMap.Map(connectionList[i].TargetId);
weightArr[i] = connectionList[i].Weight;
}
connIdArrays = new ConnectionIdArrays(srcIdArr, tgtIdArr);
}