| /* |
| * Copyright 2009-2010 by The Regents of the University of California |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * you may obtain a copy of the License from |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package edu.uci.ics.hyracks.storage.am.lsm.invertedindex.search; |
| |
| import edu.uci.ics.hyracks.storage.am.lsm.invertedindex.api.IInvertedIndexSearchModifier; |
| |
| public class JaccardSearchModifier implements IInvertedIndexSearchModifier { |
| |
| private float jaccThresh; |
| |
| public JaccardSearchModifier(float jaccThresh) { |
| this.jaccThresh = jaccThresh; |
| } |
| |
| @Override |
| public int getOccurrenceThreshold(int numQueryTokens) { |
| return Math.max((int) Math.floor((float) numQueryTokens * jaccThresh), 1); |
| } |
| |
| @Override |
| public int getNumPrefixLists(int occurrenceThreshold, int numInvLists) { |
| if (numInvLists == 0) { |
| return 0; |
| } |
| return numInvLists - occurrenceThreshold + 1; |
| } |
| |
| @Override |
| public short getNumTokensLowerBound(short numQueryTokens) { |
| return (short) Math.floor(numQueryTokens * jaccThresh); |
| } |
| |
| @Override |
| public short getNumTokensUpperBound(short numQueryTokens) { |
| return (short) Math.ceil(numQueryTokens / jaccThresh); |
| } |
| |
| public float getJaccThresh() { |
| return jaccThresh; |
| } |
| |
| public void setJaccThresh(float jaccThresh) { |
| this.jaccThresh = jaccThresh; |
| } |
| |
| @Override |
| public String toString() { |
| return "Jaccard Search Modifier, Threshold: " + jaccThresh; |
| } |
| } |