Esempio n. 1
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  @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());
    }
  }
Esempio n. 2
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 @Override
 protected void cleanup(Context context) throws IOException, InterruptedException {
   for (Text text : topN.values()) {
     context.write(NullWritable.get(), text);
   }
 }