public double Calculate(string bigramm)
{
var bigrammWords = bigramm.Split(' ');
if (bigrammWords.Count() != 2)
throw new ArgumentException("Для оценки частоты биграммы необходимо два слова.");
var otherBigrammsLeftLemm = _words.Where(t => t != bigrammWords[1]).Select(t => bigrammWords[0] + ' ' + t).ToList();
var otherBigrammsRightLemm = _words.Where(t => t != bigrammWords[0]).Select(t => t + ' ' + bigrammWords[1]).ToList();
var _wordsWithoutBigrammWords = _words.Where(t => !bigrammWords.Contains(t)).ToList();
var otherBigramms = new List<string>(); //_wordsWithoutBigrammWords.SelectMany(t => _wordsWithoutBigrammWords, (t, w) => t + ' ' + w).ToList();
for(int i = 0; i < _words.Count - 1; i++)
{
var otherBigrammText = _words[i] + " " + _words[i + 1];
if (otherBigrammText != bigramm)
otherBigramms.Add(otherBigrammText);
}
Frequency freq = new Frequency(_words);
var a = freq.GetByBigramm(bigramm);
var b = otherBigrammsLeftLemm.Sum(t => freq.GetByBigramm(t));
var c = otherBigrammsRightLemm.Sum(t => freq.GetByBigramm(t));
var d = otherBigramms.Sum(t => freq.GetByBigramm(t));
return a * Math.Log(a + 1)
+ b * Math.Log(b + 1)
+ c * Math.Log(c + 1)
+ d * Math.Log(d + 1)
- (a + b) * Math.Log(a + b + 1)
- (a + c) * Math.Log(a + c + 1)
- (b + d) * Math.Log(b + d + 1)
- (c + d) * Math.Log(c + d + 1)
+ (a + b + c + d) * Math.Log(a + b + c + d + 1);
}
public double Calculate(string word, int collectionLength, int usedCount)
{
Frequency freq = new Frequency(_words);
double f = freq.GetByOneWord(word);
double TF = f / _words.Count;
double IDF = Math.Log((collectionLength - usedCount)/usedCount);
return TF * IDF;
}
/// <summary>
/// Вычисляет коэффициент взаимной информации
/// </summary>
/// <param name="bigramm"></param>
/// <returns></returns>
public double Calculate(string bigramm)
{
var freq = new Frequency(_words);
var bigramWords = bigramm.Split(' ');
var f1 = freq.GetByOneWord(bigramWords[0]);
var f2 = freq.GetByOneWord(bigramWords[1]);
var f12 = freq.GetByBigramm(bigramm);
return Math.Log(((double)f12 * N) / (f1 * f2), 2);
}
