how to create inverted index in java

Question

I want to build an inverted index in java. I have cran data of 1400 text files. I was able to count the frequency of each term/word. I have been able to return the number times a word appears in the entire collection, but I have not been able to return which documents the word appears in. This is the code I have so far:

I want the output in the following form term1: doc1:2, doc2:3 term2: doc1:3, doc4:1 ............... so on

here term is a word in a doc file and doc 1:2 means term1 appears in doc 1 2 times

public static void main(String[]args) throws FileNotFoundException{
        Map<String, Integer> m = new HashMap<>();

        String wrd;

        for(int i=1;i<=2;i++){
           //FileInputStream tdfr = new FileInputStream("D:\\logs\\steem"+i+".txt");
           Scanner tdsc=new Scanner(new File("D:\\logs\\steem"+i+".txt"));
           while(tdsc.hasNext()){
              // m.clear();
              Integer docid=i;

               wrd=tdsc.next();
               //Vector<Integer> vPosList = p.hPosList.get(wrd);
               Integer freq=m.get(wrd);

               //Integer doc=m1.get(i);
              //System.out.println(m.get(wrd));
               m.put(wrd, (freq == null) ? 1 : freq + 1);
           }

          System.out.println(m.size() + " distinct words" + " steem" +i);
          System.out.println("Doc" +i+""+m);
          //System.out.println("Doc"+i+""+m1);
          m.clear();


        tdsc.close();

    }
        //System.out.println(m.size() + " distinct words");
        //System.out.println(m);
       // System.out.println(m1);

}
}

Atul Kumbhar Atul Kumbhar · Accepted Answer · 2016-10-04T00:50:27

public static void main(String[]args) throws FileNotFoundException{
    Map<String, Set<Doc>> wordDocMap = new HashMap<>();

    for(int i=1;i<=2;i++){
        Scanner tdsc = new Scanner(new File("D:\\logs\\steem"+i+".txt"));
        Doc document = new Doc("doc"+i);
        while(tdsc.hasNext()){
            String word = tdsc.next();
            document.put(word);
            Set<Doc> documents = wordDocMap.get(word);
            if(documents == null){
                documents = new HashSet<>();
                wordDocMap.put(word, documents);
            }
            documents.add(document);
        }
        tdsc.close();
    }

    StringBuilder builder = new StringBuilder();
    for(String word: wordDocMap.keySet()) {
        Set<Doc> documents = wordDocMap.get(word);
        builder.append(word + ":");
        for(Doc document:documents){
            builder.append(document.getDocName() +":"+ document.getCount(word));
            builder.append(", ");
        }
        builder.delete(builder.length()-2, builder.length()-1);
        builder.append("\n");
    }
    System.out.println(builder);
}

static class Doc {
    String docName;
    Map<String, Integer> m = new HashMap<>();

    public Doc(String docName){
        this.docName = docName;
    }

    public void put(String word) {
        Integer freq = m.get(word);
        m.put(word, (freq == null) ? 1 : freq + 1);
    }

    public Integer getCount(String word) {
        return m.get(word);
    }

    public String getDocName() {
        return this.docName;
    }
}

how to create inverted index in java

1 Answers