[LUCENE-2864] add maxtf to fieldinvertstate

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.1, 4.0-ALPHA
• Component/s: core/query/scoring
• Lucene Fields: New, Patch Available
• Assignee: Robert Muir
• Reporter: Robert Muir
• Created: 13/Jan/11 08:12
• Updated: 28/Aug/22 12:39
• Resolved: 14/Jan/11 11:22

Description

the maximum within-document TF is a very useful scoring value,
we should expose it so that people can use it in scoring

consider the following sim:

@Override
public float idf(int docFreq, int numDocs) {
  return 1.0F; /* not used */
}

@Override
public float computeNorm(String field, FieldInvertState state) {
  return state.getBoost() / (float) Math.sqrt(state.getMaxTF());
}

which is surprisingly effective, but more interesting for practical reasons.