summarizer/src/main/java/opennlp/summarization/Sentence.java

/*
 	* Licensed to the Apache Software Foundation (ASF) under one or more
 	* contributor license agreements. See the NOTICE file distributed with
 	* this work for additional information regarding copyright ownership.
 	* The ASF licenses this file to You 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 at
 	*
 	* 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 opennlp.summarization;

import java.text.BreakIterator;
import java.util.List;
import java.util.ArrayList;
import java.util.Locale;
import java.util.Objects;

import opennlp.summarization.preprocess.StopWords;
import opennlp.tools.stemmer.PorterStemmer;

/**
 * A representation of a sentence geared toward pagerank and summarization.
 */
public class Sentence {

	//sentId is always position of sentence in doc.
	private int sentId;
	private String stringVal;
	private Score pageRankScore;
	private int paragraph;
	private int paraPos;
	private boolean hasQuote;
	private double wordWt = 0;
	private int wordCnt;
	
	private final List<Sentence> links;
	
	public Sentence(){
		links = new ArrayList<>();
	}

	public Sentence(int id){
		this();
		this.sentId = id;
	}
	
	public void setSentId(int sentId) {
		this.sentId = sentId;
	}
	
	public int getSentId() {
		return sentId;
	}
	
	public void setPageRankScore(Score pageRankScore) {
		this.pageRankScore = pageRankScore;
	}
	
	public Score getPageRankScore() {
		return pageRankScore;
	}
	
	public void setParagraph(int paragraph) {
		this.paragraph = paragraph;
	}
	
	public int getParagraph() {
		return paragraph;
	}
	
	public void setParaPos(int paraPos) {
		this.paraPos = paraPos;
	}
	
	public int getParaPos() {
		return paraPos;
	}

	public void setStringVal(String stringVal) {
		this.stringVal = stringVal;
		if(stringVal.contains("\"")) this.hasQuote = true;
		this.wordCnt = calcWrdCnt(stringVal);
	}

	private int calcWrdCnt(String stringVal2) {
		int ret = 0;
		StopWords sw = StopWords.getInstance();
		String[] wrds = stringVal.split("\\s+");
		for(String wrd: wrds){
			if(!sw.isStopWord(wrd)&&!wrd.startsWith("'")&&!wrd.equals(".")&&!wrd.equals("?"))
				ret++;
		}
		return ret;
	}

	public String getStringVal() {
		return stringVal;
	}
	
	public void addLink(Sentence s)
	{
		this.links.add(s);
	}
	
	public List<Sentence> getLinks()
	{
		return this.links;
	}

	@Override
	public String toString()
	{
		return this.stringVal ;//+ "("+ this.paragraph +", "+this.paraPos+")";
	}

	public void setWordWt(double wordWt) {
		this.wordWt = wordWt;
	}

	public double getWordWt() {
		return wordWt;
	}
	
	public int getWordCnt()
	{
		return wordCnt==0? this.getStringVal().split("\\s+").length: wordCnt;
	}

	// Should add an article id to the sentence class. For now returns true if the ids are the same.
	@Override
	public boolean equals(Object o) {
		if (this == o) return true;
		if (o == null || getClass() != o.getClass()) return false;
		Sentence sentence = (Sentence) o;
		return sentId == sentence.sentId;
	}

	@Override
	public int hashCode() {
		return Objects.hash(sentId);
	}

	private static final String SPACE = " ";

	public String stem() {
		PorterStemmer stemmer = new PorterStemmer();
		StopWords sw = StopWords.getInstance();

		BreakIterator wrdItr = BreakIterator.getWordInstance(Locale.US);
		int wrdStrt = 0;
		StringBuilder b = new StringBuilder();
		wrdItr.setText(stringVal);	
		for(int wrdEnd = wrdItr.next(); wrdEnd != BreakIterator.DONE; 
				wrdStrt = wrdEnd, wrdEnd = wrdItr.next()) {
			String word = this.getStringVal().substring(wrdStrt, wrdEnd);//words[i].trim();
			word = word.replace("\"|'","");

			// Skip stop words and stem the word.
			if(sw.isStopWord(word)) continue;

			stemmer.stem(word);
			b.append(stemmer.toString());
			b.append(SPACE);
		}
		return b.toString();
	}
}