/// <summary>
/// return a stream of the statistics found when calculating type classification step.
/// </summary>
/// <param name="period_final_bigram_frequencies"></param>
/// <param name="unigram_freqs"></param>
/// <param name="N"></param>
/// <param name="cw01"></param>
/// <param name="cw1"></param>
/// <param name="p"></param>
/// <param name="p0"></param>
/// <param name="p1"></param>
/// <returns></returns>
public static IEnumerable<Type_Classification> enumerate_type_based_classification(
Frequencies<string> period_final_bigram_frequencies
, Frequencies<string> unigram_freqs
, double N
, double cw1
, double p
, double p0
, double p1
)
{
foreach (var bigram in period_final_bigram_frequencies.Generate())
{
var s = new Type_Classifier_Statistics();
s.c_w1 = cw1;
s.p = p;
s.p0 = p0;
s.p1 = p1;
s.w1 = ".";
s.w01 = bigram.Key;
// split off the ending period
s.w0 = bigram.Key.Substring(0, bigram.Key.Length-1);
s.c_w01 = bigram.Value;
// find the unigram frequency of this term.
s.c_w0 = unigram_freqs.Get(s.w0);
s.llr = LikelihoodRatio.logLambda(N, s.c_w01, s.c_w0, s.c_w1, s.p, s.p0, s.p1);
// Calculate the length penalty
s.length_penalty = 1/Math.Exp(s.w0.Length - count_internal_periods(s.w0));
// Calculate the Internal periods penalty
s.internal_periods_penalty = count_internal_periods(s.w0) + 1;
// Calculate occurrances penalty without final period
var len = s.w0.Length - count_internal_periods(s.w0);
len = (len == 0) ? 1: len;
s.with_final_period_penalty = 1/Math.Pow(len, (s.c_w0 - s.c_w01));
//if (s.with_final_period_penalty == 0)
// Console.WriteLine(s.w0);
// scaled log likelihood
s.scaled_llr = s.llr * s.length_penalty * s.internal_periods_penalty * s.with_final_period_penalty;
// calculate the final classifier for each sentence final bigram
var c = new Type_Classification();
c.statistics = s;
// annotate with the classification
if (s.scaled_llr < 0.3)
{
c.classification = "<S>";
}
else
{
if (s.w0.Length - count_internal_periods(s.w0) == 0)
c.classification = "<E>";
else
c.classification = "<A>";
}
yield return c;
}
}
public void test_create_frequency_object_from_text()
{
var text = TextExamples.emma();
var freq = new Frequencies<string>();
foreach (var token in Regex.Split(text, @"(\W+)"))
{
freq.Add(token);
}
Assert.AreEqual(freq.Count(), 2227);
Assert.AreEqual(freq.Get("and"), 47.0);
Assert.AreEqual(freq.Terms().Count(), 479);
}
public void test_add_to_frequencies()
{
var freq = new Frequencies<string>();
freq.Add("a");
Assert.AreEqual(1, freq.Get("a"));
}
