/// <summary>
/// Constructor of MarkovSegment, meant to be used by MarkovStructure
/// </summary>
/// <param name="prototypeSuccessors"></param>
internal MarkovSegment(ConcurrentDictionary <int, int> prototypeSuccessors)
{
// key is index of current ngram
// value is map<index of successor, associated weight>
// Populate successors
List <NGramSuccessor> successorList = new List <NGramSuccessor>(prototypeSuccessors.Count);
// Add successors in sorted form
NGramSuccessor.ReverseComparer reverseComparer = new NGramSuccessor.ReverseComparer();
foreach (var successor in prototypeSuccessors)
{
successorList.SortAdd(new NGramSuccessor(successor.Key, successor.Value), reverseComparer);
}
SetupSuccessorsAndRunningTotals(successorList);
}
// TODO: add summary, create unit test
public MarkovSegment Combine(MarkovSegment other,
int[] ngramOtherRemap,
int ownNGramLength)
{
if (successors.Length == 0)
{
return(other);
}
if (other.successors.Length == 0)
{
return(this);
}
// Combined list, map
// TODO: consider switching to BST structure (likely SortedSet) to prevent O(n) of list insert???
List <NGramSuccessor> combinedSuccessors = new List <NGramSuccessor>(successors)
{
Capacity = successors.Length + other.successors.Length
};
Dictionary <int, int> successorMap = new Dictionary <int, int>(successors.Length + other.successors.Length);
// Populate map with own
int ind = 0;
foreach (NGramSuccessor successor in successors)
{
// TODO: i dont think it should happen but each entry in here should be unique, maybe some sort of testing whether sucmap already has the index
successorMap[successor.successorIndex] = ind++;
}
var reverseComparer = new NGramSuccessor.ReverseComparer();
// Combine with other
foreach (NGramSuccessor otherSuccessor in other.successors)
{
int remap = ngramOtherRemap[otherSuccessor.successorIndex];
if (remap < ownNGramLength && successorMap.TryGetValue(remap, out int index))
{
// Given succeeding gram is not unique to other, and within the own, succeeded the current ngram
// Combine the weights basically
// TODO: really wanna not have O(n) but idk
// First, grab the relevant successor and remove
var ownSuccessor = combinedSuccessors[index];
combinedSuccessors.RemoveAt(index);
// Combine weights
ownSuccessor.weight += otherSuccessor.weight;
// And add back (in sorted position)
combinedSuccessors.SortAdd(ownSuccessor, reverseComparer);
}
else
{
// Either NGram is straight up unique to other, or the ngram is simply not a successor in this particular link
combinedSuccessors.SortAdd(new NGramSuccessor(remap, otherSuccessor.weight), reverseComparer);
}
}
return(new MarkovSegment(combinedSuccessors));
}
