/// <summary>
/// return a clone of the new bucket
/// </summary>
/// <param name="token"></param>
/// <returns></returns>
public override LexiconToken getClone(LexiconToken token)
{
LexiconPredicate predicateToReplace = new LexiconPredicate();
predicateToReplace.URI = token.URI;
predicateToReplace.label = token.label;
predicateToReplace.ranges = (token as LexiconPredicate).ranges.ToList();
predicateToReplace.QuestionMatch = token.QuestionMatch;
predicateToReplace.score = token.score;
predicateToReplace.domains = (token as LexiconPredicate).domains.ToList();
return predicateToReplace;
}
/// <summary>
/// get predicates is a method in lexicon class that get all predicates objects that match some words in the Question
/// </summary>
/// <param name="question">question to get matched predicates of it </param>
/// <param name="topN">the number of top matching results to be returned, default = 10</param>
/// <param name="Limit">the limit of the number of returned results in the query, default = 20</param>
/// <returns>list of top matching LexiconPredicates</returns>
public List<LexiconPredicate> getPredicates(string question, int topN = 20, int Limit = 30)
{
DateTime dt = DateTime.Now; // capturing time for testing
List<LexiconPredicate> __predicateList = new List<LexiconPredicate>();
//getting all permutation of words formed from the question string
List<string> permutationList = getPermutations(question);
//removing permutations that most propbably wont return results and will take time in querying
permutationList = trimPermutations(permutationList);
//Get the stemmed version of the question words
Dictionary<string, List<string>> stemmedWords = GetStemmedWords(question);
// to check if the predicates are filled before - so returning the matching predicates only - or not
if (predicateFilled)
{
foreach (LexiconPredicate predicate in predicateList)
{
if (permutationList.Contains(predicate.QuestionMatch))
{
__predicateList.Add(predicate);
}
}
return __predicateList;
}
else
{
string bifContainsValue = "";
// iterating over each permutation of Question left and Query them from virtuoso and return predicate list and add them
foreach (string questionleft in permutationList)
{
//Get all forms of questionLeft by replacing words with its stemmed version
bifContainsValue = ""; //empty string
bifContainsValue +="\'" + questionleft + "\'"; //add the original questionleft
//Replace words in questionleft with its stem and add it to the bifContainsValue
foreach (string word in stemmedWords.Keys)
{
if (questionleft.Contains(word))
{
foreach (string stem in stemmedWords[word]) //This is created because a wordcan has many stems (rare case)
{
bifContainsValue += "or\'" + questionleft.Replace(word, stem) + "\'";
}
}
}
string Query = "SELECT * WHERE { { " +
"?predicate <http://www.w3.org/2000/01/rdf-schema#label> ?label ." +
"?predicate <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#DatatypeProperty>." +
"?label bif:contains \"" + bifContainsValue + "\" } " +
"union {" +
"?predicate <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#ObjectProperty> ." +
"?predicate <http://www.w3.org/2000/01/rdf-schema#label> ?label ." +
"?label bif:contains \"" + bifContainsValue + "\" } " +
"union {" +
"?predicate <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/1999/02/22-rdf-syntax-ns#Property> ." +
"?predicate <http://www.w3.org/2000/01/rdf-schema#label> ?label ." +
"?label bif:contains \"" + bifContainsValue + "\" } " +
"} limit " + Limit;
//another Query to Get predicates untill deciding which of them is the best using statistics
string Query2 = "SELECT ?predicate ?label WHERE { " +
"{ ?predicate <http://www.w3.org/2000/01/rdf-schema#label> ?label . " +
"?predicate <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> ?propertyType. " +
"?label bif:contains \"" + bifContainsValue + "\" } " +
"filter ( ?propertyType = <http://www.w3.org/2002/07/owl#DatatypeProperty> || " +
"?propertyType = <http://www.w3.org/2002/07/owl#ObjectProperty> || " +
"?propertyType = <http://www.w3.org/1999/02/22-rdf-syntax-ns#Property> ) " +
"} limit " + Limit;
SparqlRemoteEndpoint remoteEndPoint = new SparqlRemoteEndpoint(new Uri("http://localhost:8890/sparql"));
try
{
//executing the Query and finding results
SparqlResultSet resultSet = remoteEndPoint.QueryWithResultSet(Query);
//iterating over matched predicates in the resultset
foreach (SparqlResult result in resultSet)
{
INode predicateURI = result.Value("predicate");
INode predicateLabel = result.Value("label");
LexiconPredicate tmplexiconpredicate = new LexiconPredicate();
// check that the property is used .. not a non-used property
bool hasResuts = false;
string checkQuery = "select distinct * where { ?x <" + predicateURI + "> ?y } limit 1 ";
QueryHandler.startConnection();
SparqlResultSet checkResults = QueryHandler.ExecuteQueryWithString(checkQuery);
QueryHandler.closeConnection();
if (checkResults.Count != 0)
{
hasResuts = true;
}
// check that the predicate doesn't exists in the predicateslist before
bool exists = false;
foreach (LexiconPredicate x in __predicateList)
{
// we added Questionmatch == question left bec new predicates may be added with better score that the old ones so this should be considered
if (x.URI == predicateURI.ToString() && x.QuestionMatch == questionleft )
{
exists = true;
break;
}
}
// adding the new predicate to the __predicatelist
if (!exists && hasResuts)
{
tmplexiconpredicate.URI = predicateURI.ToString();
tmplexiconpredicate.QuestionMatch = questionleft;
tmplexiconpredicate.label = predicateLabel.ToString();
__predicateList.Add(tmplexiconpredicate);
}
}
}
// skipping results that raised timeout exceptions
catch
{
util.log("skipped : " + questionleft + " ---- due to time out ");
}
}
util.log(" finished getting " + __predicateList.Count + " predicates " + " Time taken : " + DateTime.Now.Subtract(dt).TotalMilliseconds + " msec");
// now done of collecting predicates scoring them down and get the best n ones
this.predicateList = scorePredicates(__predicateList, topN);
this.predicateList = addDomainAndRange(this.predicateList);
util.log("total time taken :" + DateTime.Now.Subtract(dt).TotalMilliseconds.ToString() + " mSecs");
predicateFilled = true;
return this.predicateList;
}
}