如何计算Spark / Scala中记录之间的持续时间？

Question

I wanted to calculate Days_btwn_Shpmnt which is nothing but the number of days between the Ship Date. Need to calculate this across the first and second record and so on.

Can you help me how this can be done using Spark/Scala?

Thanks, Joe

Answer 1

You can accomplish this using lag function in spark. A sample script shows how it can done. Please note that the date has to be formatted in yyyy-mm-dd format for datediff function.

import org.apache.spark.sql.functions._
import org.apache.spark.sql.expressions.Window

val df = Seq((1000, "2016-01-19"), (1000, "2016-02-12"), (1000, "2016-02-18"), (1000, "2016-02-04")).toDF("product_id", "date")    
val result = df.withColumn("last_date" ,lag("date", 1).over(Window.partitionBy($"product_id").orderBy($"date"))).withColumn("daysToShipMent", datediff($"date", $"last_date"))

scala> result.select("product_id", "date", "daysToShipMent" ).show()
+----------+----------+--------------+
|product_id|      date|daysToShipMent|
+----------+----------+--------------+
|      1000|2016-01-19|          null|
|      1000|2016-02-04|            16|
|      1000|2016-02-12|             8|
|      1000|2016-02-18|             6|
+----------+----------+--------------+