public static List<string> EMTagger(List<string> sentence, HashSet<string> tags, Bigram emissionProb)
{
double prob = 0;
double valMax = 0;
List<string> argmax = new List<string>();
foreach (var word in sentence)
{
valMax = 0;
argmax.Add("STOP");
foreach (var tag in tags)
{
prob = emissionProb.Qml(word, tag);
if (prob >= valMax)
{
valMax = prob;
argmax.RemoveAt(argmax.Count - 1);
argmax.Add(tag);
}
}
}
return argmax;
}
public static List<string> Viterbi(
List<string> str,
Trigram q,
Bigram e,
Unigram freqList,
HashSet<string> tags,
bool splitRare)
{
List<string> y = new List<string>();
Dictionary<string, double> current = new Dictionary<string, double>();
Dictionary<string, double> previous = new Dictionary<string, double>();
string key;
double prob = 0;
double max = 0;
if (freqList.Contains(str[0]))
{
y.Add("STOP");
foreach (string v in tags)
{
prob = q.Qml(v, "*", "*") * e.Qml(str[0], v);
current.Add("*:" + v, prob);
if (prob >= max)
{
max = prob;
y.RemoveAt(y.Count - 1);
y.Add(v);
}
}
}
else
{
string v = (splitRare) ? ProperRare(str[0]) : "_RARE_";
y.Add(v);
prob = Math.Max(q.Qml("_RARE_", "*", "*"), 0);
current.Add("*:" + "_RARE_", prob);
}
previous = current;
current = new Dictionary<string, double>();
max = 0;
if (freqList.Contains(str[1]))
{
y.Add("STOP");
foreach (string u in tags)
{
foreach (string v in tags)
{
try
{
key = "*:" + u;
prob = previous[key] * q.Qml(v, "*", u) * e.Qml(str[1], v);
current.Add(string.Format("{0}:{1}", u, v), prob);
if (prob >= max)
{
max = prob;
y.RemoveAt(y.Count - 1);
y.Add(v);
}
}
catch (Exception)
{
continue;
}
}
}
}
else
{
string v = (splitRare) ? ProperRare(str[1]) : "_RARE_";
y.Add(v);
foreach (string u in tags)
{
try
{
key = "*:" + u;
prob = previous[key] * q.Qml(v, "*", u) * e.Qml(str[1], v);
current.Add(string.Format("{0}:{1}", u, v), prob);
if (prob >= max)
{
max = prob;
y.RemoveAt(y.Count - 1);
y.Add(v);
}
}
catch (Exception)
{
continue;
}
}
}
for (int i = 2; i < str.Count; i++)
{
previous = current;
current = new Dictionary<string, double>();
max = 0;
if (freqList.Contains(str[i]))
{
y.Add("STOP");
foreach (string v in tags)
{
foreach (string u in tags)
{
foreach (string w in tags)
{
key = w + ":" + u;
try
{
prob = previous[key] * q.Qml(v, w, u) * e.Qml(str[i], v);
}
catch (Exception)
{
prob = 0;
}
try
{
if (prob > 0)
current.Add(string.Format("{0}:{1}", u, v), prob);
}
catch (Exception)
{
if (prob > current[string.Format("{0}:{1}", u, v)])
{
current.Remove(string.Format("{0}:{1}", u, v));
current.Add(string.Format("{0}:{1}", u, v), prob);
}
}
if (prob >= max)
{
max = prob;
y.RemoveAt(y.Count - 1);
y.Add(v);
}
}
}
}
}
else
{
string v = (splitRare) ? ProperRare(str[i]) : "_RARE_";
y.Add(v);
foreach (string u in tags)
{
foreach (string w in tags)
{
key = w + ":" + u;
try
{
prob = previous[key] * q.Qml(v, w, u);
}
catch (Exception)
{
prob = 0;
}
try
{
if (prob > 0)
current.Add(string.Format("{0}:{1}", u, v), prob);
}
catch (Exception)
{
if (prob > current[string.Format("{0}:{1}", u, v)])
{
current.Remove(string.Format("{0}:{1}", u, v));
current.Add(string.Format("{0}:{1}", u, v), prob);
}
}
if (prob >= max)
{
max = prob;
y.RemoveAt(y.Count - 1);
y.Add(v);
}
}
}
}
}
return y;
}