组合部分标签向量并累加成完整向量

<strong><span style="font-size:18px;">/*** * @author YangXin * @info K-Means算法会对向量元素进行多次顺序的遍历，上次表示最适合于这种访问模式。 * 利用Mapper输出的部分向量，Reducer通过简单的拼接得到一个完整的向量。 */package unitTwelve;import java.io.IOException;import org.apache.hadoop.io.Text;import org.apache.hadoop.mapreduce.Reducer;import org.apache.mahout.math.NamedVector;import org.apache.mahout.math.Vector;import org.apache.mahout.math.VectorWritable;public class VectorReducer extends Reducer<Text, VectorWritable, Text, VectorWritable>{private VectorWritable writer = new VectorWritable();protected void reduce(Text tag, Iterable<VectorWritable> values, Context context) throws IOException, InterruptedException{Vector vector = null;for(VectorWritable partialVector : values){if(vector == null){vector = partialVector.get().like();}partialVector.get().addTo(vector);}NamedVector namedVector = new NamedVector(vector, tag.toString());writer.set(namedVector);context.write(tag, writer);}}</span></strong>