package ivory.core.tokenize;
import ivory.core.Constants;
import java.io.IOException;
import java.io.StringReader;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.log4j.Level;
import org.apache.log4j.Logger;
import org.apache.lucene.analysis.LowerCaseFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.ar.ArabicNormalizationFilter;
import org.apache.lucene.analysis.ar.ArabicStemFilter;
import org.apache.lucene.analysis.standard.StandardFilter;
import org.apache.lucene.analysis.standard.StandardTokenizer;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.util.Version;
import edu.umd.hooka.VocabularyWritable;
import edu.umd.hooka.alignment.HadoopAlign;
public class LuceneArabicAnalyzer extends ivory.core.tokenize.Tokenizer {
private static final Logger LOG = Logger.getLogger(LuceneArabicAnalyzer.class);
static{
LOG.setLevel(Level.WARN);
}
private org.apache.lucene.analysis.Tokenizer tokenizer;
@Override
public void configure(Configuration conf) {
configure(conf, null);
}
@Override
public void configure(Configuration conf, FileSystem fs) {
// read stopwords from file (stopwords will be empty set if file does not exist or is empty)
String stopwordsFile = conf.get(Constants.StopwordList);
stopwords = readInput(fs, stopwordsFile);
String stemmedStopwordsFile = conf.get(Constants.StemmedStopwordList);
stemmedStopwords = readInput(fs, stemmedStopwordsFile);
isStopwordRemoval = !stopwords.isEmpty();
isStemming = conf.getBoolean(Constants.Stemming, true);
VocabularyWritable vocab;
try {
vocab = (VocabularyWritable) HadoopAlign.loadVocab(new Path(conf.get(Constants.CollectionVocab)), fs);
setVocab(vocab);
} catch (Exception e) {
LOG.warn("No vocabulary provided to tokenizer.");
vocab = null;
}
LOG.warn("Stemming is " + isStemming + "; Stopword removal is " + isStopwordRemoval +"; number of stopwords: " + stopwords.size() +"; stemmed: " + stemmedStopwords.size());
}
@Override
public String[] processContent(String text) {
text = preNormalize(text);
tokenizer = new StandardTokenizer(Version.LUCENE_35, new StringReader(text));
TokenStream tokenStream = new LowerCaseFilter(Version.LUCENE_35, tokenizer);
String tokenized = postNormalize(streamToString(tokenStream));
StringBuilder finalTokenized = new StringBuilder();
for (String token : tokenized.split(" ")) {
if ( isStopwordRemoval() && isDiscard(false, token) ) {
continue;
}
finalTokenized.append( token + " " );
}
String stemmedTokenized = finalTokenized.toString().trim();
if (isStemming()) {
// then, run the Lucene normalization and stemming on the stopword-removed text
stemmedTokenized = stem(stemmedTokenized);
}
return stemmedTokenized.split(" ");
}
@Override
public String stem(String token) {
tokenizer = new StandardTokenizer(Version.LUCENE_35, new StringReader(token));
TokenStream tokenStream = new ArabicStemFilter(new ArabicNormalizationFilter(tokenizer));
CharTermAttribute termAtt = tokenStream.getAttribute(CharTermAttribute.class);
tokenStream.clearAttributes();
StringBuilder stemmed = new StringBuilder();
try {
while (tokenStream.incrementToken()) {
String curToken = termAtt.toString();
if ( vocab != null && vocab.get(curToken) <= 0) {
continue;
}
stemmed.append( curToken + " " );
}
}catch (IOException e) {
e.printStackTrace();
}
return stemmed.toString().trim();
}
@Override
public float getOOVRate(String text, VocabularyWritable vocab) {
int countOOV = 0, countAll = 0;
tokenizer = new StandardTokenizer(Version.LUCENE_35, new StringReader(text));
TokenStream tokenStream = new StandardFilter(Version.LUCENE_35, tokenizer);
tokenStream = new LowerCaseFilter(Version.LUCENE_35, tokenStream);
String tokenized = postNormalize(streamToString(tokenStream));
StringBuilder finalTokenized = new StringBuilder();
for (String token : tokenized.split(" ")) {
if ( isStopwordRemoval() && isDiscard(false, token) ) {
continue;
}
if (!isStemming()) {
if ( vocab != null && vocab.get(token) <= 0) {
countOOV++;
}
countAll++;
}else {
finalTokenized.append( token + " " );
}
}
if (isStemming()) {
tokenizer = new StandardTokenizer(Version.LUCENE_35, new StringReader(finalTokenized.toString().trim()));
tokenStream = new ArabicStemFilter(new ArabicNormalizationFilter(tokenizer));
CharTermAttribute termAtt = tokenStream.getAttribute(CharTermAttribute.class);
tokenStream.clearAttributes();
try {
while (tokenStream.incrementToken()) {
String curToken = termAtt.toString();
if ( vocab != null && vocab.get(curToken) <= 0) {
countOOV++;
}
countAll++;
}
} catch (IOException e) {
e.printStackTrace();
}
}
return (countOOV / (float) countAll);
}
}