Spark: Explode a dataframe array of structs and append id

Question

I currently have a dataframe with an id and a column which is an array of structs:

 root
 |-- id: integer (nullable = true)
 |-- lists: array (nullable = true)
 |    |-- element: struct (containsNull = true)
 |    |    |-- text: string (nullable = true)
 |    |    |-- amount: double (nullable = true)

Here is an example table with data:

 id | lists
 -----------
 1  | [[a, 1.0], [b, 2.0]]
 2  | [[c, 3.0]]

How do I transform the above dataframe to the one below? I need to "explode" the array and append the id at the same time.

 id | col1  | col2
 -----------------
 1  | a     | 1.0
 1  | b     | 2.0
 2  | c     | 3.0

Edited Note:

Note there is a difference between the two examples below. The first one contains "an array of structs of elements". While the later just contains "an array of elements".

 root
 |-- id: integer (nullable = true)
 |-- lists: array (nullable = true)
 |    |-- element: struct (containsNull = true)
 |    |    |-- text: string (nullable = true)
 |    |    |-- amount: double (nullable = true)


root
 |-- a: long (nullable = true)
 |-- b: array (nullable = true)
 |    |-- element: long (containsNull = true)

That question has a simpler dataframe where the second column is just an array. Mine differs because my second column is an "array of structs". — Steve
– Steve, Commented Feb 20, 2017 at 22:10

user7595317 · Accepted Answer · 2017-02-20 21:23:16Z

25

explode is exactly the function:

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

df.select($"id", explode($"lists")).select($"id", $"col.text", $"col.amount")

answered Feb 20, 2017 at 21:23

user7595317

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1 Comment

Vezir Over a year ago

I simply applied what included in the solution it works just as expected by Steve. It seperates the list into individual columns. Thanx

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