void WeightingFunctionContextBM25_dpfc::addWeightingFeature(
const std::string& name_,
PostingIteratorInterface* itr_,
float weight_,
const TermStatistics& stats_)
{
try
{
if (boost::algorithm::iequals( name_, "match"))
{
double nofMatches = stats_.documentFrequency()>=0?stats_.documentFrequency():(GlobalCounter)itr_->documentFrequency();
double idf = 0.0;
bool relevant = (m_nofCollectionDocuments * m_relevant_df_factor > nofMatches);
if (m_nofCollectionDocuments > nofMatches * 2)
{
idf = logl(
(m_nofCollectionDocuments - nofMatches + 0.5)
/ (nofMatches + 0.5));
}
if (idf < 0.00001)
{
idf = 0.00001;
}
m_weight_featar.push_back( Feature( itr_, weight_, idf, relevant));
}
else if (boost::algorithm::iequals( name_, "struct"))
{
m_struct_featar.push_back( Feature( itr_, weight_, 0.0, false));
}
else if (boost::algorithm::iequals( name_, "title"))
{
if (m_title_itr) throw strus::runtime_error( _TXT( "duplicate '%s' weighting function feature parameter '%s'"), "BM25_dpfc", name_.c_str());
m_title_itr = itr_;
}
else
{
throw strus::runtime_error( _TXT( "unknown '%s' weighting function feature parameter '%s'"), "BM25_dpfc", name_.c_str());
}
}
CATCH_ERROR_ARG1_MAP( _TXT("error adding weighting feature to '%s' weighting: %s"), "BM25_dpfc", *m_errorhnd);
}
Feature( PostingIteratorInterface* itr_, double weight_, const TermStatistics& stats_)
:m_itr(itr_),m_weight(weight_),m_df(stats_.documentFrequency()>=0?stats_.documentFrequency():std::numeric_limits<double>::quiet_NaN()),m_match(false){}
