問題描述

嘗試使用 Lucene 4.0 計算詞頻.我的文檔頻率工作得很好，但不知道如何使用 API 來做詞頻.這是我的代碼:

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();
}

我嘗試過執行類似 reader.getTermVector(0, "content")... 的操作，但找不到僅獲取該文檔中特定術語頻率的方法.

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.

謝謝！

推薦答案

K，想通了.您可以從 MultiFields 獲取 DocsEnum 對象，然后對其進行迭代.

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();
}

這篇關于Lucene 4.0 中的詞頻的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！