/// <summary>
/// Returns postings for soundex query
/// </summary>
/// <param name="name">the author name being queried</param>
public List <string> SearchSoundexQuery(string name)
{
//list of strings to return
List <String> results = new List <string>();
try
{
//get a list of postings given the name
IList <Posting> postings = new DiskSoundEx(Indexer.path).GetPostings(name);
//if the query returns any results
if (postings.Count > 0)
{
//add the number of postings to the list of strings to return
results.Add(postings.Count.ToString());
//for each posting
foreach (Posting p in postings)
{
//use the posting's id to access the document
IDocument doc = corpus.GetDocument(p.DocumentId);
//add the title and name of the author to the list of strings to be returned
results.Add(doc.Title + " (Author: " + doc.Author + ")");
//also add the document id to the list of strings to be returned
results.Add(doc.DocumentId.ToString());
}
}
else
{
//if there are no postings just return a list with a zero in it
results.Add("0");
}
//return the final list of strings
}
catch (Exception e)
{
Console.WriteLine(e);
}
return(results);
}
/// <summary>
/// Constructs an index from a corpus of documents
/// </summary>
/// <param name="corpus">a corpus to be indexed</param>
public static IIndex IndexCorpus(IDocumentCorpus corpus)
{
Console.WriteLine($"[Indexer] Indexing {corpus.CorpusSize} documents in the corpus...");
// Time how long it takes to index the corpus
Stopwatch elapsedTime = new Stopwatch();
elapsedTime.Start();
// Set the index type and token processor to use
DiskPositionalIndex index = new DiskPositionalIndex(Indexer.path);
DiskSoundEx soundEx = new DiskSoundEx(Indexer.path);
DiskKGram kGram = new DiskKGram(Indexer.path);
index.Clear();
soundEx.Clear();
kGram.Clear();
ITokenProcessor processor = new StemmingTokenProcesor();
HashSet <string> unstemmedVocabulary = new HashSet <string>();
// Index the document
foreach (IDocument doc in corpus.GetDocuments())
{
//Tokenize the documents
ITokenStream stream = new EnglishTokenStream(doc.GetContent());
IEnumerable <string> tokens = stream.GetTokens();
//keeptrack of tokens per document
int tokenCount = 0;
//keep track of file size
int position = 0;
foreach (string token in tokens)
{
tokenCount++;
//Process token to term
List <string> terms = processor.ProcessToken(token);
//Add term to the index
bool termsIsAdded = false;
foreach (string term in terms)
{
if (term.Length > 0)
{
index.AddTerm(term, doc.DocumentId, position);
termsIsAdded = true;
}
}
//Increase the position num
position = termsIsAdded ? position + 1 : position;
//Keep track of vocabularies for K-gram
foreach (string term in ((NormalTokenProcessor)processor).ProcessToken(token))
{
unstemmedVocabulary.Add(term);
}
}
//Add token count per document
index.AddTokensPerDocument(doc.DocumentId, tokenCount);
//get number of bytes in file
string docFilePath = doc.FilePath;
int fileSizeInByte = (int)(new FileInfo(docFilePath).Length / 8f);
index.AddByteSize(doc.DocumentId, fileSizeInByte);
//calculates Average term Frequency for a specific document
index.CalcAveTermFreq(doc.DocumentId);
//calculate L_{d} for the document and store it index so that we can write it to disk later
index.CalculateDocWeight(doc.DocumentId);
Indexer.averageDocLength = index.calculateAverageDocLength();
//Add author to SoundEx Index
soundEx.AddDocIdByAuthor(doc.Author, doc.DocumentId);
stream.Dispose();
}
kGram.buildKGram(unstemmedVocabulary);
index.Save();
soundEx.Save();
elapsedTime.Stop();
Console.WriteLine("[Indexer] Done Indexing! Time Elapsed " + elapsedTime.Elapsed.ToString("mm':'ss':'fff"));
GC.Collect();
return(index);
}
