如何從spark scala中的數據框中查找短語計數？

Question

如何從數據框中的列中查找字數？

我試圖從DF下面的評論欄中找到單詞的計數

CustID -  Comments

101    [[Nice one, Nice One,Nice]]

102    [[This was nice, Nice]

這是我試圖在上面的用例中實現的代碼

val result = DF1.withColumn("Count of comments ",  DF1("Comments")).map(events => (events,1)).reduce

在這里，我無法在元組頂部應用'reduceByKey'函數，只有'reduce'函數列出

這是我想要實現的預期輸出

CustID  -   Comments                      -  Count of comments**
101         [[Nice one, Nice One,Nice]]      Nice one 2, Nice 1
102         [[This was nice, Nice]           This was nice 1, Nice

任何人都可以幫助我並提供正確的建議來實現上述輸出嗎？

Answer 1

請在此處找到解決方案：

源數據修剪大括號后看起來像這樣：

+------+----------------------+
|CustID|Comments              |
+------+----------------------+
|101   |Nice one,Nice One,Nice|
|102   |This was nice, Nice   |
+------+----------------------+

代碼如下所示：

  def countElments(row: Row): Row =
  {
    val str:String = row.getAs[String]("Comments")
    val list=str.split("\\,").map(_.toLowerCase()).toList
    val newCol=list.groupBy(identity).mapValues(_.size).mkString(",")
    Row.merge(row, Row(newCol))
  }

val rdd=df.rdd.map(row =>countElments(row))
val newSchema=df.schema.add("Count of comments", StringType, true)
val final_df=spark.createDataFrame(rdd, newSchema)
final_df.show(false)

輸出如下所示：

+------+----------------------+-----------------------------+
|CustID|Comments              |Count of comments            |
+------+----------------------+-----------------------------+
|101   |Nice one,Nice One,Nice|nice -> 1,nice one -> 2      |
|102   |This was nice, Nice   |this was nice -> 1, nice -> 1|
+------+----------------------+-----------------------------+