如何将Scala函数应用于两个不同列的数据帧Scala

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

// 创建SparkSession
val spark = SparkSession.builder()
  .appName("DataFrame Example")
  .getOrCreate()

// 创建两个数据帧
val df1 = spark.createDataFrame(Seq(
  (1, "John", 25),
  (2, "Jane", 30),
  (3, "Bob", 35)
)).toDF("id", "name", "age")

val df2 = spark.createDataFrame(Seq(
  (1, "New York"),
  (2, "London"),
  (3, "Tokyo")
)).toDF("id", "city")

// 定义一个Scala函数
val concatNameAndCity = udf((name: String, city: String) => s"$name, $city")

// 应用函数到两个不同列的数据帧
val result = df1.join(df2, Seq("id"))
  .withColumn("name_and_city", concatNameAndCity(col("name"), col("city")))

// 显示结果
result.show()