如何使用Scala计算Spark中数据帧中列的起始索引和结束索引之间的平均行数？

import org.apache.spark.sql.{DataFrame, SparkSession}
import org.apache.spark.sql.functions._

val spark = SparkSession.builder()
  .appName("Calculate Average Rows")
  .getOrCreate()

val dataFrame: DataFrame = spark.read.format("csv")
  .option("header", "true")
  .load("path/to/your/data.csv")

val startIndex = 2 // 起始索引
val endIndex = 5 // 结束索引

val averageRows = dataFrame.select(
  avg(row_number().over(Window.orderBy(monotonically_increasing_id())).alias("row_number")))
  .filter(col("row_number").between(startIndex, endIndex))
  .first()
  .getDouble(0)

println(s"The average number of rows between index $startIndex and $endIndex is: $averageRows")