public void map(Object key, Text value, Context context)
				throws IOException, InterruptedException {
			String[] data = parser.parseLine(value.toString());
			String origin = data[PreProcessing.INDEX_ORIGIN];
			String dest = data[PreProcessing.INDEX_DEST];
			if (origin.equalsIgnoreCase("origin") || dest.equalsIgnoreCase("dest"))
				return;
			context.write(new Text(origin), NullWritable.get());
			context.write(new Text(dest), NullWritable.get());
		}