Spark dataframe为每个现有行添加一行

您可以创建另一个 dataframe 需要使用的更改 withColumn union 二者都 dataframes 像

import sqlContext.implicits._
import org.apache.spark.sql.functions._

val df = Seq(
  (1, "in", 55),
  (2, "in", 54)
).toDF("groupid", "unit", "height")

val df2 = df.withColumn("unit", lit("cm")).withColumn("height", col("height")*2.54)

df.union(df2).show(false)

+-------+----+------+
|groupid|unit|height|
+-------+----+------+
|1      |in  |55.0  |
|2      |in  |54.0  |
|1      |cm  |139.7 |
|2      |cm  |137.16|
+-------+----+------+