我需要从现有的DataFrame创建一个DataFrame,我需要在其中更改模式。
我有一个像DataFrame:
+-----------+----------+-------------+
|Id |Position |playerName |
+-----------+-----------+------------+
|10125 |Forward |Messi |
|10126 |Forward |Ronaldo |
|10127 |Midfield |Xavi |
|10128 |Midfield |Neymar |
我使用下面给出的案例类创建了这个:
case class caseClass (
Id: Int = "",
Position : String = "" ,
playerName : String = ""
)
现在我需要在Struct类型下同时制作Playername和position。
即
我需要用schema创建另一个DataFrame,
根
| - Id:int(nullable = true)
| - playerDetails:struct(nullable = true)
| | --playername:string(nullable = true)
| | --Position:string(nullable = true)
我通过引用链接https://medium.com/@mrpowers/adding-structtype-columns-to-spark-dataframes-b44125409803执行以下代码来创建新的数据帧
myschema是
List(
StructField("Id", IntegerType, true),
StructField("Position",StringType, true),
StructField("playerName", StringType,true)
)
我尝试了以下代码
spark.sparkContext.parallelize(data),
myschema
)
但我无法实现。
我看到类似的问题Change schema of existing dataframe但我无法理解解决方案。
是否有任何解决方案直接在case类中实现StructType?所以我认为我不需要为创建结构类型值创建自己的模式。
可以使用函数“struct”:
// data
val playersDF = Seq(
(10125, "Forward", "Messi"),
(10126, "Forward", "Ronaldo"),
(10127, "Midfield", "Xavi"),
(10128, "Midfield", "Neymar")
).toDF("Id", "Position", "playerName")
// action
val playersStructuredDF = playersDF.select($"Id", struct("playerName", "Position").as("playerDetails"))
// display
playersStructuredDF.printSchema()
playersStructuredDF.show(false)
输出:
root
|-- Id: integer (nullable = false)
|-- playerDetails: struct (nullable = false)
| |-- playerName: string (nullable = true)
| |-- Position: string (nullable = true)
+-----+------------------+
|Id |playerDetails |
+-----+------------------+
|10125|[Messi, Forward] |
|10126|[Ronaldo, Forward]|
|10127|[Xavi, Midfield] |
|10128|[Neymar, Midfield]|
+-----+------------------+