Spark nested complex dataframe

Question

I am trying to get the complex data into normal dataframe format

My data schema:

root
 |-- column_names: array (nullable = true)
 |    |-- element: string (containsNull = true)
 |-- values: array (nullable = true)
 |    |-- element: array (containsNull = true)
 |    |    |-- element: string (containsNull = true)
 |-- id: array (nullable = true)
 |    |-- element: string (containsNull = true)

My Data File(JSON Format):

{"column_names":["2_col_name","3_col_name"],"id":["a","b","c","d","e"],"values":[["2_col_1",1],["2_col_2",2],["2_col_3",9],["2_col_4",10],["2_col_5",11]]}

I am trying to convert above data into this format:

+----------+----------+----------+
|1_col_name|2_col_name|3_col_name|
+----------+----------+----------+
|         a|   2_col_1|         1|
|         b|   2_col_2|         2|
|         c|   2_col_3|         9|
|         d|   2_col_4|        10|
|         e|   2_col_5|        11|
+----------+----------+----------+

I tried using explode function on id and values but got different output as below:

+---+-------------+
| id|       values|
+---+-------------+
|  a| [2_col_1, 1]|
|  a| [2_col_2, 2]|
|  a| [2_col_3, 9]|
|  a|[2_col_4, 10]|
|  a|[2_col_5, 11]|
|  b| [2_col_1, 1]|
|  b| [2_col_2, 2]|
|  b| [2_col_3, 9]|
|  b|[2_col_4, 10]|
+---+-------------+
only showing top 9 rows

Not sure where i am doing wrong

blackbishop · Accepted Answer · 2021-03-02 06:28:12Z

2

You can use array_zip + inline functions to flatten then pivot the column names :

val df1 = df.select(
    $"column_names",
    expr("inline(arrays_zip(id, values))")
  ).select(
    $"id".as("1_col_name"),
    expr("inline(arrays_zip(column_names, values))")
  )
  .groupBy("1_col_name")
  .pivot("column_names")
  .agg(first("values"))

df1.show
//+----------+----------+----------+
//|1_col_name|2_col_name|3_col_name|
//+----------+----------+----------+
//|e         |2_col_5   |11        |
//|d         |2_col_4   |10        |
//|c         |2_col_3   |9         |
//|b         |2_col_2   |2         |
//|a         |2_col_1   |1         |
//+----------+----------+----------+

answered Mar 2, 2021 at 6:28

blackbishop

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