sparkDataframe生成

我有两个Dataframe： dataframe1 有70000行，如：

location_id, location, flag
1,Canada,active
2,Paris,active
3,London,active
4,Berlin,active

第二测向 lookup 已修改每个位置的ID（此Dataframe会不时修改），例如：

id,location
1,Canada
10,Paris
4,Berlin
3,London

我的问题是，我需要把新的身份证作为 lookup 如果 location_id 不同于 id 然后，对于每个位置，保持标志名称为非活动的对应位置的旧id（以维护历史数据）和标志名称为活动的新id。因此，配置单元中的输出表应该如下所示：

location_id,location,flag
1,Canada,active
2,Paris,inactive
10,Paris,active
3,London,active
4,Berlin,active

我试着先加入两个框架。然后在加入df时，我正在执行操作，以将所有记录保存在配置单元中。我尝试了以下操作：

val joinedFrame = dataframe1.join(lookup, "location")
val df_temp = joinedFrame.withColumn("flag1", when($"tag_id" === $"tag_number", "active").otherwise("inactive"))
var count = 1
df_temp.foreach(x => {
  val flag1 = x.getAs[String]("flag1").toString
  val flag = x.getAs[String]("flag").toString
  val location_id = x.getAs[String]("location_id").toString
  val location = x.getAs[String]("location").toString
  val id = x.getAs[String]("id").toString
  if ((count != 1)&&(flag1 != flag)){
    println("------not equal-------",flag1,"-------",flag,"---------",id,"---------",location,"--------",location_id)
    val df_main = sc.parallelize(Seq((location_id, location,flag1), (id, location, flag))).toDF("location_id", "location", "flag")
    df_main.show
    df_main.write.insertInto("location_coords")
  }
  count += 1
})

它打印具有不同ID的位置值，但在将这些值保存为Dataframe时，我遇到了一个异常：

not equal------inactive------active---10---------Paris---------2    
17/09/29 03:43:29 ERROR Executor: Exception in task 0.0 in stage 25.0 (TID 45)
    java.lang.NullPointerException
            at $line83.$read$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$anonfun$1.apply(<console>:75)
            at $line83.$read$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$anonfun$1.apply(<console>:65)
            at scala.collection.Iterator$class.foreach(Iterator.scala:893)
            at scala.collection.AbstractIterator.foreach(Iterator.scala:1336)
            at org.apache.spark.rdd.RDD$$anonfun$foreach$1$$anonfun$apply$28.apply(RDD.scala:918)
            at org.apache.spark.rdd.RDD$$anonfun$foreach$1$$anonfun$apply$28.apply(RDD.scala:918)
            at org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:1951)
            at org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:1951)
            at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:87)
            at org.apache.spark.scheduler.Task.run(Task.scala:99)
            at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:322)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
            at java.lang.Thread.run(Thread.java:748)
    17/09/29 03:43:29 WARN TaskSetManager: Lost task 0.0 in stage 25.0 (TID 45, localhost, executor driver): java.lang.NullPointerException
            at $line83.$read$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$anonfun$1.apply(<console>:75)
            at $line83.$read$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$anonfun$1.apply(<console>:65)
            at scala.collection.Iterator$class.foreach(Iterator.scala:893)
            at scala.collection.AbstractIterator.foreach(Iterator.scala:1336)
            at org.apache.spark.rdd.RDD$$anonfun$foreach$1$$anonfun$apply$28.apply(RDD.scala:918)
            at org.apache.spark.rdd.RDD$$anonfun$foreach$1$$anonfun$apply$28.apply(RDD.scala:918)
            at org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:1951)
            at org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:1951)
            at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:87)
            at org.apache.spark.scheduler.Task.run(Task.scala:99)
            at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:322)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
            at java.lang.Thread.run(Thread.java:748)

根据你的意见，我认为最简单的方法是 join 而是在身份证上。在执行外部联接时，缺少的列将以null结束，这些行是您感兴趣的已更新行。
在这之后，剩下的就是更新location列（如果它是空的）以及flag列，请参见下面的代码（注意，我稍微更改了列名）：

val spark = SparkSession.builder.getOrCreate()
import spark.implicits._

val df = Seq((1,"Canada","active"),(2,"Paris","active"),(3,"London","active"),(4,"Berlin","active"))
  .toDF("id", "location", "flag")
val df2 = Seq((1,"Canada"),(10,"Paris"),(4,"Berlin"),(3,"London"))
  .toDF("id", "location_new") 

val df3 = df.join(df2, Seq("id"), "outer")
  .filter($"location".isNull or $"location_new".isNull)
  .withColumn("location", when($"location_new".isNull, $"location").otherwise($"location_new"))
  .withColumn("flag", when($"location" === $"location_new", "active").otherwise("inactive"))
  .drop("location_new")

> df3.show()
+---+--------+--------+
| id|location|    flag|
+---+--------+--------+
| 10|   Paris|  active|
|  2|   Paris|inactive|
+---+--------+--------+

在此之后，您可以使用这个新的Dataframe来更新配置单元表。

sparkDataframe生成

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