public List <SearchResult> ExecuteTfIdfSearch(int?windowSize = null, byte?filterByClass = null)
{
var idfs = Query.Select(x => (token: x, idf: Index.Idf(x))).ToDictionary(x => x.token, x => x.idf);
var queryVector = new TfIdfVector(idfs, QueryTokenCounts);
var docIds = new HashSet <int>();
foreach (var token in Query)
{
foreach (var docId in Index.SearchByToken(token))
{
docIds.Add(docId);
}
}
if (windowSize.HasValue)
{
docIds = ProximityFilter(docIds, windowSize.Value);
}
var scoresByDocId = new Dictionary <int, double>();
foreach (var docId in docIds)
{
var tfByToken = new Dictionary <string, int>();
foreach (var token in Query)
{
tfByToken.Add(token, Index.GetOccurrence(token, docId).Positions.Count);
}
var docVector = new TfIdfVector(idfs, tfByToken);
scoresByDocId.Add(docId, docVector.Multiply(queryVector));
}
if (filterByClass == null)
{
return(scoresByDocId.OrderByDescending(x => x.Value).Select(x => new SearchResult(x.Key, Index.GetHighlight(x.Key), x.Value)).ToList());
}
var documents = docIds.Select(x => new DocumentWrapper(Index.PureDocumentsById[x])).ToDictionary(x => x.Document.Id);
var vectorGenerator = new VectorGenerator(documents, true);
vectorGenerator.Process();
var tokenMapper = new TokenMapper();
var classifier = new RandomForestClassifierClient();
var result = classifier.Classify(documents.Values.Select(x => x.CreateClassificationVector(tokenMapper)).ToList());
for (int i = 0; i < result.Count; i++)
{
documents.Values.ElementAt(i).ClassifiedTag = result[i];
}
var filteredResult = scoresByDocId.Where(x => documents[x.Key].ClassifiedTag == filterByClass).ToList();
Console.WriteLine($"Removed {filteredResult.Count} items with other classes");
return(filteredResult.OrderByDescending(x => x.Value).Select(x => new SearchResult(x.Key, Index.GetHighlight(x.Key), x.Value)).ToList());
}
internal double Multiply(TfIdfVector queryVector)
{
double sum = 0;
foreach (var token in queryVector.FinalVector.Keys)
{
sum += queryVector.FinalVector[token] * this.FinalVector[token];
}
return(sum);
}
internal TfIdfVector Add(TfIdfVector other, int sourceWeight)
{
var result = new Dictionary <string, double>();
foreach (var key in this.FinalVector.Keys.Union(other.FinalVector.Keys))
{
double finalValue = 0.0;
if (this.FinalVector.TryGetValue(key, out double currentValue))
{
finalValue += sourceWeight * currentValue;
}
if (other.FinalVector.TryGetValue(key, out double otherValue))
{
finalValue += otherValue;
}
result.Add(key, finalValue);
}
return(new TfIdfVector(result));
}