Lucene 4.0中的术语频率 [英] Term frequency in Lucene 4.0

问题描述

尝试使用Lucene 4.0计算术语频率。我的文档频率工作得很好，但无法弄清楚如何使用API​​进行术语频率。这是我的代码：

Trying to calculate term frequency using Lucene 4.0. I got document frequency working just fine, but can't figure out how to do term frequency using the API. Here's the code I have:

private static void addDoc(IndexWriter writer, String content) throws IOException {
    FieldType fieldType = new FieldType();
    fieldType.setStoreTermVectors(true);
    fieldType.setStoreTermVectorPositions(true);
    fieldType.setIndexed(true);
    fieldType.setIndexOptions(IndexOptions.DOCS_AND_FREQS);
    fieldType.setStored(true);
    Document doc = new Document();
    doc.add(new Field("content", content, fieldType));
    writer.addDocument(doc);
}

public static void main(String[] args) throws IOException, ParseException {
    Directory directory = new RAMDirectory();  
    Analyzer analyzer = new WhitespaceAnalyzer(Version.LUCENE_40);
    IndexWriterConfig config = new IndexWriterConfig(Version.LUCENE_40, analyzer);
    IndexWriter writer = new IndexWriter(directory, config);
    addDoc(writer, "Lucene is stupid");
    addDoc(writer, "Java is great");
    writer.close();
    IndexReader reader = DirectoryReader.open(directory);
    System.out.println(reader.docFreq(new Term("content", "Lucene")));
    reader.close();
}

我尝试过像 reader.getTermVector （0，content）... 但找不到一种方法来获取该文档中特定术语的频率。

I've tried doing something like reader.getTermVector(0, "content")... but can't find a method to just get the frequency of a particular term in that document.

谢谢！

推荐答案

K，想通​​了。您可以从 MultiFields 中获取 DocsEnum 对象，然后对其进行迭代。

K, figured it out. You can get a DocsEnum object from MultiFields, and then iterate over that.

private static void addDoc(IndexWriter writer, String content) throws IOException {
    FieldType fieldType = new FieldType();
    fieldType.setStoreTermVectors(true);
    fieldType.setStoreTermVectorPositions(true);
    fieldType.setIndexed(true);
    fieldType.setIndexOptions(IndexOptions.DOCS_AND_FREQS);
    fieldType.setStored(true);
    Document doc = new Document();
    doc.add(new Field("content", content, fieldType));
    writer.addDocument(doc);
}

public static void main(String[] args) throws IOException, ParseException {
    Directory directory = new RAMDirectory();  
    Analyzer analyzer = new WhitespaceAnalyzer(Version.LUCENE_40);
    IndexWriterConfig config = new IndexWriterConfig(Version.LUCENE_40, analyzer);
    IndexWriter writer = new IndexWriter(directory, config);
    addDoc(writer, "bla bla bla bleu bleu");
    addDoc(writer, "bla bla bla bla");
    writer.close();
    DirectoryReader reader = DirectoryReader.open(directory);
    DocsEnum de = MultiFields.getTermDocsEnum(reader, MultiFields.getLiveDocs(reader), "content", new BytesRef("bla"));
    int doc;
    while((doc = de.nextDoc()) != DocsEnum.NO_MORE_DOCS) {
          System.out.println(de.freq());
    }
    reader.close();
}

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