在Spark数据框中修改结构列 [英] Modify a struct column in spark dataframe

问题描述

我有一个pyspark数据框，其中包含学生"列，如下所示:

I have a pyspark dataframe which contains a column "student" as follows:

"student" : {
   "name" : "kaleem",
   "rollno" : "12"
}

在数据框中的架构为:

structType(List(
   name: String, 
   rollno: String))

我需要将此列修改为

"student" : {
   "student_details" : {
         "name" : "kaleem",
         "rollno" : "12"
   }
}

数据框中的架构必须为:

Schema for this in dataframe must be :

structType(List(
  student_details: 
     structType(List(
         name: String, 
         rollno: String))
))

如何在火花中做到这一点?

How to do this in spark?

推荐答案

使用

Use named_struct function to achieve this-

val  data =
      """
        | {
        |   "student": {
        |       "name": "kaleem",
        |       "rollno": "12"
        |   }
        |}
      """.stripMargin
    val df = spark.read.json(Seq(data).toDS())
    df.show(false)
    println(df.schema("student"))

输出-

+------------+
|student     |
+------------+
|[kaleem, 12]|
+------------+

StructField(student,StructType(StructField(name,StringType,true), StructField(rollno,StringType,true)),true)

2.使用named_struct

更改架构

2. change the schema using named_struct

val processedDf = df.withColumn("student",
      expr("named_struct('student_details', student)")
    )
    processedDf.show(false)
    println(processedDf.schema("student"))

输出-

+--------------+
|student       |
+--------------+
|[[kaleem, 12]]|
+--------------+

StructField(student,StructType(StructField(student_details,StructType(StructField(name,StringType,true), StructField(rollno,StringType,true)),true)),false)

对于python step#2来说，就像删除val一样工作

For python step#2 will work as is just remove val

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