火花更改 DF 模式列从点重命名为下划线

Question

我有一个 dataframe 列名有dot 。 示例：df.printSchema

user.id_number
user.name.last
user.phone.mobile

等，我想通过用_替换dot来重命名架构。

user_id_number
user_name_last
user_phone_mobile

注意：这个 DF 的输入数据是 JSON 格式（与NoSQL等非关系数据）

Answer 1

使用.map,.withColumnRenamed替换. 与_

Example:

val df=Seq(("1","2","3")).toDF("user.id_number","user.name.last","user.phone.mobile")
df.toDF(df.columns.map(x =>x.replace(".","_")):_*).show()

//using replaceAll
df.toDF(df.columns.map(x =>x.replaceAll("\\.","_")):_*).show()
//+--------------+--------------+-----------------+
//|user_id_number|user_name_last|user_phone_mobile|
//+--------------+--------------+-----------------+
//|             1|             2|                3|
//+--------------+--------------+-----------------+

2. Using selectExpr:

val expr=df.columns.map(x =>col(s"`${x}`").alias(s"${x}".replace(".","_")).toString)

df.selectExpr(expr:_*).show()
//+--------------+--------------+-----------------+
//|user_id_number|user_name_last|user_phone_mobile|
//+--------------+--------------+-----------------+
//|             1|             2|                3|
//+--------------+--------------+-----------------+

3.Using.withColumnRenamed:

df.columns.foldLeft(df){(tmpdf,col) =>tmpdf.withColumnRenamed(col,col.replace(".","_"))}.show()
//+--------------+--------------+-----------------+
//|user_id_number|user_name_last|user_phone_mobile|
//+--------------+--------------+-----------------+
//|             1|             2|                3|
//+--------------+--------------+-----------------+