I have a json dataset, and it is formated as:
val data = spark.read.json("user.json").select("user_id","friends").show()
+--------------------+--------------------+
| user_id| friends|
+--------------------+--------------------+
|18kPq7GPye-YQ3LyK...|[rpOyqD_893cqmDAt...|
|rpOyqD_893cqmDAtJ...|[18kPq7GPye-YQ3Ly...|
|4U9kSBLuBDU391x6b...|[18kPq7GPye-YQ3Ly...|
|fHtTaujcyKvXglE33...|[18kPq7GPye-YQ3Ly...|
+--------------------+--------------------+
data: org.apache.spark.sql.DataFrame = [user_id: string, friends: array<string>]
How can I transform it to [user_id: String, friend: String], eg:
+--------------------+--------------------+
| user_id| friend|
+--------------------+--------------------+
|18kPq7GPye-YQ3LyK...| rpOyqD_893cqmDAt...|
|18kPq7GPye-YQ3LyK...| 18kPq7GPye-YQ3Ly...|
|4U9kSBLuBDU391x6b...| 18kPq7GPye-YQ3Ly...|
|fHtTaujcyKvXglE33...| 18kPq7GPye-YQ3Ly...|
+--------------------+--------------------+
How can I get this dataframe?