@Override
protected void map(LongWritable key, Text value, Context context)
throws IOException, InterruptedException {
String line = value.toString();
// assume each input page of interest has one keyword, followed by a tab,
// and multiple document ids separated by comma.
String[] fields = line.split("\t", -1);
String docId = fields[0];
double pageRank = Double.valueOf(fields[1]);
// add this record to local top N map
topN.put(pageRank, new Text(docId + "\t" + pageRank));
// if we have more than N records in top N now, remove the lowest
if (topN.size() > N) {
topN.remove(topN.firstKey());
}
}
@Override
protected void cleanup(Context context) throws IOException, InterruptedException {
for (Text text : topN.values()) {
context.write(NullWritable.get(), text);
}
}