Get the elements from different arraytype columns and build a column with heterogeneous data in Spark

0
votes

I have a Spark dataframe parsed from an XML file which has data in the below format:

+---------+------------------------------------------------------------------------------------------+----------------------------+------------------------------------------------+
|id       |a                                                                                         |b                           |c                                               |
+---------+------------------------------------------------------------------------------------------+----------------------------+------------------------------------------------+
|191683250|[52396062, 55064266, 51149167, 53441347, 51309543, 51517728, 51543627, 68138995, 70180065]|[2, 2, 1, 3, 3, 2, 2, 27, 1]|[1.15, 0.8, 4.0, 2.49, 1.0, 2.8, 0.4, 0.49, 2.0]|
+---------+------------------------------------------------------------------------------------------+----------------------------+------------------------------------------------+

I need the output data in the format:

+---------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|id       |a                                                                                                                                                                          |
+---------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|191683250|Array[(52396062,2,1.5), (55064266,2,0.8),  (51149167,1,4.0),  (53441347,3,2.49), (51309543,3,1.0), (51517728,2,2.8), (51543627,2,0.4), (68138995,27,0.49), (70180065,1,2.0)]|
+---------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

ie., I need an Array of StructTypes/tuples. Im just stuck on how to proceed on this.

Could you please point me how can I achieve this in Spark using Scala. Appreciate any help.

2
scalaapache-sparkapache-spark-sql

2 Answers

4
votes

In Spark >= 2.4 this can be solved using the arrays_zip function:

val df = // Example dataframe in question
val df2 = df.withColumn("a", arrays_zip($"a", $"b", $"c"))
  .drop("b", "c")

For older versions of Spark, use an UDF:

val convertToArray = udf((a: Seq[Int], b: Seq[Int], c: Seq[Double]) => {
  a zip b zip c map { case((a,b),c) => (a,b,c)}
})

val df = // Example dataframe in question
val df2 = df.withColumn("a", convertToArray($"a", $"b", $"c"))
  .drop("b", "c")

The resulting dataframe:

+---------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|id       |a                                                                                                                                                                     |
+---------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|191683250|[[52396062,2,1.15], [55064266,2,0.8], [51149167,1,4.0], [53441347,3,2.49], [51309543,3,1.0], [51517728,2,2.8], [51543627,2,0.4], [68138995,27,0.49], [70180065,1,2.0]]|
+---------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1
votes

This answer is not as perfect as @Shaido's answer. This answer is just a possibility of doing in another way

df.select($"id",
  array(struct($"a"(0), $"b"(0), $"c"(0)),
  struct($"a"(1), $"b"(1), $"c"(1)),
  struct($"a"(2), $"b"(2), $"c"(2)),
  struct($"a"(3), $"b"(3), $"c"(3)),
  struct($"a"(4), $"b"(4), $"c"(4)),
  struct($"a"(5), $"b"(5), $"c"(5)),
  struct($"a"(6), $"b"(6), $"c"(6)),
  struct($"a"(7), $"b"(7), $"c"(7))).as("a"))
.show(false)

You should be getting

+---------+----------------------------------------------------------------------------------------------------------------------------------------------------+
|id       |a                                                                                                                                                   |
+---------+----------------------------------------------------------------------------------------------------------------------------------------------------+
|191683250|[[52396062,2,1.15], [55064266,2,0.8], [51149167,1,4.0], [53441347,3,2.49], [51309543,3,1.0], [51517728,2,2.8], [51543627,2,0.4], [68138995,27,0.49]]|
+---------+----------------------------------------------------------------------------------------------------------------------------------------------------+