我正在尝试计算维基百科文档之间的行相似性。我有格式为Key class: class org.apache.hadoop.io.Text Value Class: class org.apache.mahout.math.VectorWritable的tf-idf矢量。我从这里开始快速浏览文本分析：https://cwiki.apache.org/confluence/display/MAHOUT/Quick+tour+of+text+analysis+using+the+Mahout+command+line
我创建了一个mahout矩阵，如下所示：
mahout rowid
-i wikipedia-vectors/tfidf-vectors/part-r-00000
-o wikipedia-matrix
我得到了生成的行和列数：
vectors.RowIdJob: Wrote out matrix with 4587604 rows and 14121544 columns to wikipedia-matrix/matrix
矩阵的格式为Key class: class org.apache.hadoop.io.IntWritable Value Class: class org.apache.mahout.math.VectorWritable
我还有一个docIndex文档，格式如下：Key class: class org.apache.hadoop.io.IntWritable Value Class: class org.apache.hadoop.io.Text
然后当我运行行相似性作业时
mahout rowsimilarity
-i wikipedia-matrix/matrix
-o wikipedia-similarity
-r 4587604
--similarityClassname SIMILARITY_COSINE
-m 50
-ess
我得到以下错误：
13/08/25 15:18:18 INFO mapred.JobClient: Task Id : attempt_201308161435_0364_m_000001_1, Status : FAILED
java.lang.ClassCastException: org.apache.hadoop.io.Text cannot be cast to org.apache.mahout.math.VectorWritable
at org.apache.mahout.math.hadoop.similarity.cooccurrence.RowSimilarityJob$VectorNormMapper.map(RowSimilarityJob.java:183)
at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:144)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:648)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:322)
at org.apache.hadoop.mapred.Child$4.run(Child.java:266)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1278)
at org.apache.hadoop.mapred.Child.main(Child.java:260)
有人能帮我纠正这个错误吗？当输入矩阵的格式为Key class: class org.apache.hadoop.io.IntWritable Value Class: class org.apache.mahout.math.VectorWritable 时，我不确定这个org.apache.hadoop.io.Text在哪里
非常感谢。
最佳，Dragan
我使用以下命令解决了它：
hadoop jar mahout-examples-0.9-SNAPSHOT.jar
org.apache.mahout.math.hadoop.similarity.cooccurrence.RowSimilarityJob
-i /user/dmilchev/wikipedia-matrix/matrix
-o /user/dmilchev/wikipedia-similarity
-r 4587604 --similarityClassname SIMILARITY_COSINE -m 50 -ess
我没有犯任何错误。