創建火花數據幀基於條件

Question

我有2個數據幀： dataframe1具有70000行，如：

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

對於每個位置二DF lookup已修改IDS（此數據幀被修改的時間到時間），像：

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

我的問題是，我需要從lookup LOCATION_ID新的ID，如果location_id比id不同的，那麼，保持CORRE的老ID標誌名稱爲非活動狀態（維護歷史數據）的新位置和標誌名稱爲每個位置活動的新標識。因此，蜂巢中的輸出表應該如下所示：

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

我試圖先加入兩個幀。然後在加入DF，我執行行動，保存在hive.I嘗試操作的所有記錄：

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 
}) 

它打印出具有不同ID的位置值，但同時節省了這些值數據框中，我獲得例外：

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) 

Answer 1

根據您的意見，我認爲最簡單的方法是使用ids代替join。在進行外連接時，缺失的列最終會爲空，這些行是已更新並且您感興趣的行。

之後，剩下的全部內容是更新位置列，以防萬一它爲空還有標誌欄，看到我的代碼如下（請注意，我有所改變的列名）：

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| 
+---+--------+--------+ 

在此之後，你可以使用這個新的數據框更新蜂巢表。