【发布时间】：2018-03-19 09:21:05
【问题描述】：
我试图了解输入 .csv 文件上的 K-means 聚类，该文件由 56376 行和两列组成，第一列表示 id，第二列表示一组单词/此数据的示例如下所示
**1。 1428951621 记得 2013 年 4 月 19 日来到米兰 5 月 16 日星期一
- 1429163429 rt windeerlust sehun hyungluhan yessehun 甚至记得
今天**
处理这些数据的 Scala 代码如下所示
val inputData = sc.textFile("test.csv")
// this is a changable parameter for the number of clusters to use for kmeans
val numClusters = 4;
// number of iterations for the kmeans
val numIterations = 10;
// this is the size of the vectors to be created by Word2Vec this is tunable
val vectorSize = 600;
val filtereddata = inputData.filter(!_.isEmpty).
map(line=>line.split(",",-1)).
map(line=>(line(1),line(1).split(" ").filter(_.nonEmpty)))
val corpus = inputData.filter(!_.isEmpty).
map(line=>line.split(",",-1)).
map(line=>line(1).split(" ").toSeq)
val values:RDD[Seq[String]] = filtereddata.map(s=>s._2)
val keys = filtereddata.map(s=>s._1)
/*******************Word2Vec and normalisation*****************************/
val w2vec = new Word2Vec().setVectorSize(vectorSize);
val model = w2vec.fit(corpus)
val outtest:RDD[Seq[Vector]]= values.map(x=>x.map(m=>try {
model.transform(m)
} catch {
case e: Exception => Vectors.zeros(vectorSize)
}))
val convertest = outtest.map(m=>m.map(x=>(x.toArray)))
val withkey = keys.zip(convertest)
val filterkey = withkey.filter(!_._2.isEmpty)
val keysfinal= filterkey.map(x=>x._1)
val valfinal= filterkey.map(x=>x._2)
// for each collections of vectors that is one tweet, add the vectors
val reducetest = valfinal.map(x=>x.reduce((a,b)=>a.zip(b).map(t=>t._1+t._2)))
val filtertest = reducetest.map(x=>x.map(m=>(m,x.length)).map(m=>m._1/m._2))
val test = filtertest.map(x=>new DenseVector(x).asInstanceOf[Vector])
val normalizer = new Normalizer()
val data1= test.map(x=>(normalizer.transform(x)))
/*********************Clustering Algorithm***********************************/
val clusters = KMeans.train(data1,numClusters,numIterations)
val predictions= clusters.predict(data1)
val clustercount= keysfinal.zip(predictions).distinct.map(s=>(s._2,1)).reduceByKey(_+_)
val result= keysfinal.zip(predictions).distinct
result.saveAsTextFile(fileToSaveResults)
val wsse = clusters.computeCost(data1)
println(s"The number of clusters is $numClusters")
println("The cluster counts are:")
println(clustercount.collect().mkString(" "))
println(s"The wsse is: $wsse")
但是经过一些迭代后，它会抛出“java.lang.NullPointerException”并在第 36 阶段退出。错误如下所示：
17/10/07 14:42:10 INFO TaskSchedulerImpl: Adding task set 26.0 with 2 tasks
17/10/07 14:42:10 INFO TaskSetManager: Starting task 0.0 in stage 26.0 (TID 50, localhost, partition 0, ANY, 5149 bytes)
17/10/07 14:42:10 INFO TaskSetManager: Starting task 1.0 in stage 26.0 (TID 51, localhost, partition 1, ANY, 5149 bytes)
17/10/07 14:42:10 INFO Executor: Running task 1.0 in stage 26.0 (TID 51)
17/10/07 14:42:10 INFO Executor: Running task 0.0 in stage 26.0 (TID 50)
17/10/07 14:42:10 INFO deprecation: mapred.output.dir is deprecated. Instead, use mapreduce.output.fileoutputformat.outputdir
17/10/07 14:42:10 INFO deprecation: mapred.output.key.class is deprecated. Instead, use mapreduce.job.output.key.class
17/10/07 14:42:10 INFO deprecation: mapred.output.value.class is deprecated. Instead, use mapreduce.job.output.value.class
17/10/07 14:42:10 INFO deprecation: mapred.working.dir is deprecated. Instead, use mapreduce.job.working.dir
17/10/07 14:42:10 INFO ShuffleBlockFetcherIterator: Getting 2 non-empty blocks out of 2 blocks
17/10/07 14:42:10 INFO ShuffleBlockFetcherIterator: Started 0 remote fetches in 1 ms
17/10/07 14:42:10 INFO ShuffleBlockFetcherIterator: Getting 2 non-empty blocks out of 2 blocks
17/10/07 14:42:10 INFO ShuffleBlockFetcherIterator: Started 0 remote fetches in 1 ms
17/10/07 14:42:10 ERROR Executor: Exception in task 0.0 in stage 26.0 (TID 50)
java.lang.NullPointerException
at java.lang.ProcessBuilder.start(ProcessBuilder.java:1012)
at org.apache.hadoop.util.Shell.runCommand(Shell.java:404)
请帮助我在此代码中本地化问题，因为我无法理解。 注意：这段代码是别人写的
【问题讨论】：
标签： java scala apache-spark cluster-analysis k-means