Xapian_tutorial_2

The expand of synonym(同义词)

  • such as ‘I love you‘ and ‘ILU’
  • process to do this
    • Write the synonym into database
      • use WriteDatabase::add_synonym(term,synonym)
      • but we can only do ‘I love you’ –> ‘ILU’
        • if we want to reverse it, we need to add the reverse version

use the synonym when query

  • use QueryParser::set_database() to set db
  • when using the QueryParser::set_database(), the second parameter use FLAG_SYNONYM or FLAG_AUTO_SYNONYMS
  • FLAG_SYNONYM is the ~WORD format in the query sentence. expend the synonym of the word automatically
  • FLAG_AUTO_SYNONYMS is expend all the phrase, do not need to write ~

sample

  • makefile 
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    all:
      g++ -o index -I/usr/local/include -l xapian index.cpp
      g++ -o query -I/usr/local/include -l xapian query.cpp
    clean:
      rm -rf index index_data/ query
  • index.cpp
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 #include<xapian.h>
 #include<iostream>
 #include<string>
 using namespace std;
 #define CONTENT "70:69， I love you This is man basketball race history the smallest point difference race ， smile to last is east man Chinese 。 Which can be said ， This time is the most famous victory and can be said this is the most lucky resuly 。After the end of the game, the coach of the Chinese aa and The boss bb hang togetherm and the two guy are so happy that the chinese win。"
 #define INDEX_PATH "./index_data"
 #define WORD1 "I love you"
 #define WORD2 "ILU"
int main(int argc, char *argv[]){
try{
  //The text to be indexed
  string content(CONTENT);

  //open a database and write
  Xapian::WritableDatabase db(string(INDEX_PATH), Xapian::DB_CREATE_OR_OPEN);
  
  //term generator
  Xapian::TermGenerator indexer;

  //add synonym
  db.add_synonym(string(WORD1), string(WORD2));

  //Make document
  Xapian::Document doc;
  doc.set_data(content);
  indexer.set_document(doc);
  indexer.index_text(content);

  //add document to db
  db.add_document(doc);

  //flush to disk
  db.commit();

}catch(const Xapian::Error &e){
  cout<<e.get_description()<<endl;
}
return 0;}
  • query.cpp
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 #include<xapian.h>
 #include<iostream>
 #include<string>
using namespace std;
 #define QUERY "~ILU AND Chinese"
 #define INDEX_PATH "./index_data"
 #define F_DOCID 1
int main(){
  
try{
  //The string for query
  string query_str(QUERY);
  //open the database
  Xapian::Database db(string(INDEX_PATH));
  
  //open search handle
  Xapian::Enquire enquire(db);

  //Parser Query
  Xapian::QueryParser qp;
  qp.set_database(db);
  Xapian::Query query = qp.parse_query(query_str, Xapian::QueryParser::FLAG_SYNONYM);
  cout<<"Query is "<<query.get_description()<<endl;

  //find the top 10 result
  enquire.set_query(query);
  Xapian::MSet result = enquire.get_mset(0,10);
  cout<<result.get_matches_estimated()<<" result found"<<endl;

  //print the result
  for(Xapian::MSetIterator iter = result.begin(); iter != result.end(); iter++){
      Xapian::Document doc = iter.get_document();
      cout<<iter.get_rank()<<": docid "<<doc.get_value(F_DOCID)<<", data"<<doc.get_data()<<endl;
  }

}catch(const Xapian::Error e){
  cout<<e.get_description()<<endl;
}
return 0;
}
c++, search_engine
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