/// <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 assumed 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 = DirectedGraphUtils.CompileNodeIdMap_InputOutputCount_HiddenNodeIdArr(
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(connIdArrays, inputCount, outputCount, totalNodeCount));
}
// Notes.
// Array.Sort() can sort a secondary array, but here we need to sort a third array; the below code
// does this but performs a lot of unnecessary memory allocation and copying. As such this logic was
// replaced (see current implementation of SharpNeat.Network.ConnectionSorter) with a customised sort
// routine that is faster and more efficient w.r.t memory allocations and copying.
public static void Sort <S>(ConnectionIdArrays connIdArrays, S[] weightArr) where S : struct
{
// Init array of indexes.
int[] srcIdArr = connIdArrays._sourceIdArr;
int[] tgtIdArr = connIdArrays._targetIdArr;
int[] idxArr = new int[srcIdArr.Length];
for (int i = 0; i < idxArr.Length; i++)
{
idxArr[i] = i;
}
// Sort the array of indexes based on the connections that each index points to.
var comparer = new ConnectionComparer(connIdArrays);
Array.Sort(idxArr, comparer);
int len = srcIdArr.Length;
int[] srcIdArr2 = new int[len];
int[] tgtIdArr2 = new int[len];
S[] weightArr2 = new S[len];
for (int i = 0; i < len; i++)
{
int j = idxArr[i];
srcIdArr2[i] = srcIdArr[j];
tgtIdArr2[i] = tgtIdArr[j];
weightArr2[i] = weightArr[j];
}
Array.Copy(srcIdArr2, srcIdArr, len);
Array.Copy(tgtIdArr2, tgtIdArr, len);
Array.Copy(weightArr2, weightArr, len);
}
public static void Sort(ConnectionIdArrays connIdArrays, T[] secondaryArr)
{
Debug.Assert(connIdArrays._sourceIdArr != null);
Debug.Assert(connIdArrays._targetIdArr != null);
Debug.Assert(secondaryArr != null);
Debug.Assert(connIdArrays._sourceIdArr.Length == connIdArrays._targetIdArr.Length);
Debug.Assert(connIdArrays._sourceIdArr.Length == secondaryArr.Length);
IntrospectiveSort(connIdArrays._sourceIdArr, connIdArrays._targetIdArr, secondaryArr, 0, connIdArrays._sourceIdArr.Length);
}
internal DirectedGraph(
ConnectionIdArrays connIdArrays,
int inputCount,
int outputCount,
int totalNodeCount)
{
_connIdArrays = connIdArrays;
_inputCount = inputCount;
_outputCount = outputCount;
_totalNodeCount = totalNodeCount;
}
/// <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);
}
public ConnectionComparer(ConnectionIdArrays connIdArrays)
{
_srcIdArr = connIdArrays._sourceIdArr;
_tgtIdArr = connIdArrays._targetIdArr;
}