Split multiple array columns into rows

Question

This is a question identical to

Pyspark: Split multiple array columns into rows

but I want to know how to do it in scala

for a dataframe like this,

 +---+---------+---------+---+
 |  a|        b|        c|  d|
 +---+---------+---------+---+
 |  1|[1, 2, 3]|[, 8, 9] |foo|
 +---+---------+---------+---+

I want to have it in following format

+---+---+-------+------+
|  a|  b|  c    |    d |
+---+---+-------+------+
|  1|  1|  None |  foo |
|  1|  2|  8    |  foo |
|  1|  3|  9    |  foo |
+---+---+-------+------+

In scala, I know there's an explode function, but I don't think it's applicable here.

I tried

import org.apache.spark.sql.functions.arrays_zip

but I get an error, saying arrays_zip is not a member of org.apache.spark.sql.functions although it's clearly a function in https://spark.apache.org/docs/latest/api/java/org/apache/spark/sql/functions.html

None in an integer list is conflicting, anyway considered it as 0 and proceeded updated the answer. — sathya
– sathya, Commented Aug 12, 2020 at 18:25
@smart_coder how do you replace None with integer or some other string value in scala? — user98235
– user98235, Commented Aug 12, 2020 at 20:58
I am just wondering that how this seq [,8,9] list got generated?! — sathya
– sathya, Commented Aug 12, 2020 at 21:08

sathya · Accepted Answer · 2020-08-12 18:26:46Z

1

the below answer might be helpful to you,

import org.apache.spark.sql.types._
import org.apache.spark.sql.Row
import org.apache.spark.sql.functions._
 
val arrayData = Seq(
      Row(1,List(1,2,3),List(0,8,9),"foo"))
val arraySchema = new StructType().add("a",IntegerType).add("b", ArrayType(IntegerType)).add("c", ArrayType(IntegerType)).add("d",StringType)

val df = spark.createDataFrame(spark.sparkContext.parallelize(arrayData),arraySchema)

df.select($"a",$"d",explode($"b",$"c")).show(false)

val zip = udf((x: Seq[Int], y: Seq[Int]) => x.zip(y))

df.withColumn("vars", explode(zip($"b", $"c"))).select($"a", $"d",$"vars._1".alias("b"), $"vars._2".alias("c")).show()

/*
+---+---+---+---+
|  a|  d|  b|  c|
+---+---+---+---+
|  1|foo|  1|  0|
|  1|foo|  2|  8|
|  1|foo|  3|  9|
+---+---+---+---+
*/

answered Aug 12, 2020 at 18:26

sathya

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