问题
I am trying to get a term-document matrix from Lucene. It seems that most of the SO questions are for outdated APIs with different classes. I tried combining insight from these two questions to get a term vector from every document:
- Term Vector Frequency in Lucene 4.0
- Is it possible to iterate through documents stored in Lucene Index?
Relevant code, but DocEnum is not recognized in the current API. How can I get a term vector or count of all terms for every document?
IndexReader reader = DirectoryReader.open(index);
for (int i = 0; i < reader.maxDoc(); i++) {
Document doc = reader.document(i);
Terms terms = reader.getTermVector(i, "country_text");
if (terms != null && terms.size() > 0) {
// access the terms for this field
TermsEnum termsEnum = terms.iterator();
BytesRef term = null;
// explore the terms for this field
while ((term = termsEnum.next()) != null) {
// enumerate through documents, in this case only one
DocsEnum docsEnum = termsEnum.docs(null, null);
int docIdEnum;
while ((docIdEnum = docsEnum.nextDoc()) != DocIdSetIterator.NO_MORE_DOCS) {
// get the term frequency in the document
System.out.println(term.utf8ToString()+ " " + docIdEnum + " " + docsEnum.freq());
}
}
}
}
Full code:
import java.io.*;
import java.util.Iterator;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.StringField;
import org.apache.lucene.document.TextField;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.Terms;
import org.apache.lucene.index.TermsEnum;
import org.apache.lucene.queryparser.classic.ParseException;
import org.apache.lucene.queryparser.classic.QueryParser;
import org.apache.lucene.search.BooleanClause;
import org.apache.lucene.search.BooleanQuery;
import org.apache.lucene.search.FuzzyQuery;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.TermQuery;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.RAMDirectory;
import org.apache.lucene.util.BytesRef;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.JSONValue;
import org.json.simple.parser.JSONParser;
public class LuceneIndex {
public static void main(String[] args) throws IOException, ParseException {
String jsonFilePath = "wiki_data.json";
JSONParser parser = new JSONParser();
// Specify the analyzer for tokenizing text.
StandardAnalyzer analyzer = new StandardAnalyzer();
// create the index
Directory index = new RAMDirectory();
IndexWriterConfig config = new IndexWriterConfig(analyzer);
IndexWriter w = new IndexWriter(index, config);
try {
JSONArray a = (JSONArray) parser.parse(new FileReader(jsonFilePath));
for (Object o : a) {
JSONObject country = (JSONObject) o;
String countryName = (String) country.get("country_name");
String cityName = (String) country.get("city_name");
String countryText = (String) country.get("country_text");
String cityText = (String) country.get("city_text");
System.out.println(cityName);
addDoc(w, countryName, cityName, countryText, cityText);
}
w.close();
IndexReader reader = DirectoryReader.open(index);
for (int i = 0; i < reader.maxDoc(); i++) {
Document doc = reader.document(i);
Terms terms = reader.getTermVector(i, "country_text");
if (terms != null && terms.size() > 0) {
// access the terms for this field
TermsEnum termsEnum = terms.iterator();
BytesRef term = null;
// explore the terms for this field
while ((term = termsEnum.next()) != null) {
// enumerate through documents, in this case only one
DocsEnum docsEnum = termsEnum.docs(null, null);
int docIdEnum;
while ((docIdEnum = docsEnum.nextDoc()) != DocIdSetIterator.NO_MORE_DOCS) {
// get the term frequency in the document
System.out.println(term.utf8ToString()+ " " + docIdEnum + " " + docsEnum.freq());
}
}
}
}
// reader can be closed when there
// is no need to access the documents any more.
reader.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (org.json.simple.parser.ParseException e) {
e.printStackTrace();
}
}
private static void addDoc(IndexWriter w, String countryName, String cityName,
String countryText, String cityText) throws IOException {
Document doc = new Document();
doc.add(new StringField("country_name", countryName, Field.Store.YES));
doc.add(new StringField("city_name", cityName, Field.Store.YES));
doc.add(new TextField("country_text", countryText, Field.Store.YES));
doc.add(new TextField("city_text", cityText, Field.Store.YES));
w.addDocument(doc);
}
}
回答1:
First thank for your code I had a little bug and your code helped me to complete it.
For me it works with this: (Lucene 7.2.1)
for(int i = 0; i < reader.maxDoc(); i++){
Document doc = reader.document(i);
Terms terms = reader.getTermVector(i, "text");
if (terms != null && terms.size() > 0) {
// access the terms for this field
TermsEnum termsEnum = terms.iterator();
BytesRef term = null;
// explore the terms for this field
while ((term = termsEnum.next()) != null) {
// enumerate through documents, in this case only one
PostingsEnum docsEnum = termsEnum.postings(null);
int docIdEnum;
while ((docIdEnum = docsEnum.nextDoc()) != DocIdSetIterator.NO_MORE_DOCS) {
// get the term frequency in the document
System.out.println(term.utf8ToString()+ " " + docIdEnum + " " + docsEnum.freq());
}
}
}
}
The Change here is I used PostingsEnum. DocsEnum is not available in Lucene 7.2.1 anymore.
But why it didn't work for you is how you add your document:
private void addDoc(IndexWriter w, String text, String name, String id) throws IOException {
Document doc = new Document();
// Create own FieldType to store Term Vectors
FieldType ft = new FieldType();
ft.setIndexOptions(IndexOptions.DOCS_AND_FREQS);
ft.setTokenized(true);
ft.setStored(true);
ft.setStoreTermVectors(true); //Store Term Vectors
ft.freeze();
StoredField t = new StoredField("text",text,ft);
doc.add(t);
doc.add(new StringField("name", name, Field.Store.YES));
doc.add(new StringField("id", id, Field.Store.YES));
w.addDocument(doc);
}
You have to create your own FieldType. None of the standard ones will save the term vectors.
回答2:
According to this question you should not use TextField for term frequency. Because it does not calculate it. Use "Field".
回答3:
You can also do it by make your field as this:
FieldType myFieldType = new FieldType(TextField.TYPE_STORED);
myFieldType.setStoreTermVectors(true);
Then re-index your documents. finally can get term vector!
来源：https://stackoverflow.com/questions/47321816/term-document-matrix-in-lucene