How to make the first n words more important in Lucene

Question

I want to make the first n (which i set) words from a document more important that the rest of the document in Lucene. How will i do that? I found something about boosting, but boost a field to be more important. My document is supposed to be an only field. Is to number the words at indexing time and boost them a solution? Something like that:

TextField myField = new TextField("text",termAtt.toString(),Store.YES);

myField.setBoost(2);

document.add(myField);

if the i didn't reach the n-th word in my document? I want to get the following result: let's say that the first 20 words in a document are more important than the rest. I have 2 identical documents that have more than 20 words and i add the word that i am searching in one document as th first word and in the second document as the last word, an i want that the first document to have a bigger score.

femtoRgon femtoRgon · Accepted Answer · 2014-05-26T05:29:26

The best approach would be to simply create two different fields, one containing the higher value portion of the text (this wouldn't need to be stored), and the next containing the full text:

int leadinLength = 20
TextField myFieldLeadin = new TextField("text_leadin",termAtt.toString().substring(leadinLength,Store.NO);
TextField myField = new TextField("text, termAtt.toString(),Store.YES);
myFieldLeadin.setBoost(2);
document.add(myFieldLeadin);
document.add(myField);

To could use a MultiFieldQueryParser to streamline searching in both fields at once, if desired, like:

Query query = MultiFieldQueryParser.parse(Version.LUCENE_48, "my search query",{"text_leadin","text"}, analyzer);
TopDocs docs = searcher.search(query, 10);

How to make the first n words more important in Lucene

1 Answers