文本预处理，去除词频数为１的文档_freqlist类怎么去除词频为1的词

package clustering.garbage
 
import java.io.PrintWriter
 
import org.apache.spark.SparkContext
 
/**
  * Created by fhqplzj on 17-1-12 at 下午8:40.
  */
object Lines {
  def main(args: Array[String]): Unit = {
    val sc = new SparkContext("local[*]", s"${getClass.getSimpleName.stripSuffix("$")}")
    val path = "/tmp/fuck"
    removeRareWords(sc, path)
  }
 
  /**
    * 去除词频数为１的单词，单词之间以空格分割，行之间以换行符分割
    *
    * @param sc
    * @param path
    */
  def removeRareWords(sc: SparkContext, path: String): Unit = {
    val docs = sc.wholeTextFiles(path)
    /*词频数为１的单词组成的集合*/
    val rareWords = docs.
      values.
      flatMap(_.split("\\s+")).
      map((_, 1)).
      reduceByKey(_ + _).
      filter(_._2 == 1).
      keys.
      collect().
      toSet
    docs.foreach {
      case (name, doc) =>
        val printer = new PrintWriter(name.substring(name.indexOf("/")))
        val content = doc.split("\n").map(_.split(" ").filterNot(rareWords.contains).mkString(" ")).mkString("\n")
        printer.print(content)
        printer.close()
    }
  }
}