/// <summary>
/// Normalize pair frequency according to the frequencies of words derived from
/// a corpus and the branching factor of extracted relations.
/// sim = (2*mean_i(b_i)/(b_i+b_j)) * P(r_ij)/(P(w_i)*P(w_j))
/// where P(r_ij) = r_ij / sum_ij(r_ij), P(w_i) = f_i / sum_i(f_i),
/// b_i is the number of extractions with frequency more than minFreq.
/// </summary>
public void rerankEfreqCfreqRnum(string corpusFreqFile, int minFreq)
{
if (isTransformed)
{
Console.WriteLine("These raw frequency scores of this relation collection are already normalized");
return;
}
// Load the word frequencies
var corpusFreq = new IVocabulary(corpusFreqFile, false);
// Get number of extractions per term with frequency for than minFreq
Dictionary <string, int> relationsNum = getRelationsNum(minFreq);
// Calculate mean number of relations per word
int[] branchesArray = relationsNum.Values.ToArray();
double meanBranchesNum = (double)branchesArray.Sum() / branchesArray.Length;
// Probabilities of words
double meanProb = corpusFreq.getMeanFreq() / corpusFreq.getTokensNum();
var corpusProb = corpusFreq.getProb();
// Probability of relations
this.normProb();
// Reranking
int missingWordsNum = 0;
double targetProb = 0;
double relatumProb = 0;
double prevRnum = 1;
double targetRnum;
double relatumRnum;
foreach (var target in this)
{
foreach (var relatum in target.Value)
{
targetProb =
(corpusProb.ContainsKey(target.Key) ? corpusProb [target.Key] : meanProb);
relatumProb =
(corpusProb.ContainsKey(relatum.Key) ? corpusProb [relatum.Key] : meanProb);
if (corpusProb.ContainsKey(relatum.Key) || corpusProb.ContainsKey(target.Key))
{
missingWordsNum++;
}
if (relationsNum.ContainsKey(target.Key) && relationsNum.ContainsKey(relatum.Key))
{
targetRnum = relationsNum[target.Key];
relatumRnum = relationsNum[relatum.Key];
}
else if (relationsNum.ContainsKey(target.Key))
{
Console.WriteLine("Warning: Input file is not symmetric for word '{0}'. Reranking may be wrong.", relatum.Key);
targetRnum = relationsNum[target.Key];
relatumRnum = targetRnum;
}
else
{
Console.WriteLine("Error: can not compute relation frequency for the words '{0}' and {1}. Reranking may be wrong.",
target.Key, relatum.Key);
targetRnum = prevRnum;
relatumRnum = prevRnum;
}
relatum.Value.sim =
(2 * meanBranchesNum / (targetRnum + relatumRnum)) * (relatum.Value.sim / (targetProb + relatumProb));
}
}
isTransformed = true;
}
/// <summary>
/// Normalize pair frequency according to the frequencies of words derived from
/// a corpus (used for extraction) or an extraction concordance.
/// type == 1: sim = r_ij/(f_i + f_j), where w_i -- is the number of
/// times the word w_i appeared in the corpus/concordance.
/// type == 2: sim = P(r_ij)/(P(w_i)P(w_j)
/// type == 3: sim = -log P(r_ij)/(P(w_i)P(w_j)
/// where P(r_ij) = r_ij / sum_ij(r_ij), P(w_i) = f_i / sum_i(f_i)
/// </summary>
public void rerankEfreqCfreq(string corpusFreqFile, int type)
{
if (isTransformed)
{
Console.WriteLine("These raw frequency scores of this relation collection are already normalized");
return;
}
// Load the word frequencies
var corpusFreq = new IVocabulary(corpusFreqFile, false);
// Reranking
double meanFreq = corpusFreq.getMeanFreq();
Console.WriteLine("mean frequency={0}", meanFreq);
int missingWordsNum = 0;
if (type == 1)
{
double targetFreq = 0;
double relatumFreq = 0;
foreach (var target in this)
{
foreach (var relatum in target.Value)
{
targetFreq =
(corpusFreq.ContainsKey(target.Key) ? corpusFreq [target.Key] [IVocabulary.FREQ] : meanFreq);
relatumFreq =
(corpusFreq.ContainsKey(relatum.Key) ? corpusFreq [relatum.Key] [IVocabulary.FREQ] : meanFreq);
if (corpusFreq.ContainsKey(relatum.Key) || corpusFreq.ContainsKey(target.Key))
{
missingWordsNum++;
}
relatum.Value.sim =
relatum.Value.sim / (targetFreq + relatumFreq);
}
}
}
else if (type == 2 || type == 3)
{
double targetProb = 0;
double relatumProb = 0;
double meanProb = meanFreq / corpusFreq.getTokensNum();
var corpusProb = corpusFreq.getProb();
this.normProb();
foreach (var target in this)
{
foreach (var relatum in target.Value)
{
targetProb =
(corpusProb.ContainsKey(target.Key) ? corpusProb [target.Key] : meanProb);
relatumProb =
(corpusProb.ContainsKey(relatum.Key) ? corpusProb [relatum.Key] : meanProb);
if (corpusProb.ContainsKey(relatum.Key) || corpusProb.ContainsKey(target.Key))
{
missingWordsNum++;
}
relatum.Value.sim =
relatum.Value.sim / (targetProb + relatumProb);
if (type == 3)
{
relatum.Value.sim = -Math.Log(relatum.Value.sim);
}
}
}
}
else
{
Console.WriteLine("Error: wrong type of normalization.");
return;
}
Console.WriteLine("missing words = {0}", missingWordsNum);
isTransformed = true;
}
