public string ClassifyArticle(PreprocessedArticle article)
{
KnnArticle knnArticle = new KnnArticle {
Label = article.Label, FeaturesVector = FeaturesVectorService.GetFeaturesVector(article)
};
List <(string, double)> neighbors = new List <(string, double)>();
foreach (KnnArticle classifiedArticle in ClassifiedArticles)
{
neighbors.Add((classifiedArticle.PredictedLabel, Metric.CalculateDistance(classifiedArticle.FeaturesVector, knnArticle.FeaturesVector)));
}
var orderedNeighbors = neighbors.OrderBy(t => t.Item2).Take(K).ToList();
var distinctNeighborsCount = orderedNeighbors.GroupBy(t => t.Item1).Select(g => (g.Key, g.Count())).OrderByDescending(e => e.Item2).ToList();
var neighborsWithSameCount =
distinctNeighborsCount.Where(t => t.Item2 == distinctNeighborsCount[0].Item2).ToList();
if (neighborsWithSameCount.Count != 1)
{
var orderedNeighborsWithSameCount =
orderedNeighbors.Where(c => neighborsWithSameCount.Select(d => d.Item1).Contains(c.Item1));
var distinctNeighborsSum = orderedNeighborsWithSameCount.GroupBy(t => t.Item1).Select(g => (g.Key, g.Sum(t => t.Item2))).OrderBy(e => e.Item2).ToList();
knnArticle.PredictedLabel = distinctNeighborsSum[0].Item1;
ClassifiedArticles.Add(knnArticle);
return(distinctNeighborsSum[0].Item1);
}
knnArticle.PredictedLabel = distinctNeighborsCount[0].Item1;
ClassifiedArticles.Add(knnArticle);
return(distinctNeighborsCount[0].Item1);
}
public void InitKnn(List <PreprocessedArticle> articles)
{
coldStartNumber = articles.Count;
ClassifiedArticles = articles.Select(t => new KnnArticle()
{
Label = t.Label, PredictedLabel = t.Label, FeaturesVector = FeaturesVectorService.GetFeaturesVector(t)
}).ToList();
}
public KnnService(FeaturesVectorService featuresVectorService, IMetric metric, int k)
{
FeaturesVectorService = featuresVectorService;
Metric = metric;
K = k;
}