更新时间:2023-02-03 10:04:58
在 Spark 2.1+ 中,您可以使用以下方法对单个 Array 列中的值进行串联:
In Spark 2.1+ to do the concatenation of the values in a single Array column you can use the following:
concat_ws
标准函数map
运算符使用 concat_ws 函数.
concat_ws(sep: String, exprs: Column*): Column 使用给定的分隔符将多个输入字符串列连接成一个字符串列.
concat_ws(sep: String, exprs: Column*): Column Concatenates multiple input string columns together into a single string column, using the given separator.
val solution = words.withColumn("codes", concat_ws(" ", $"rate_plan_code"))
scala> solution.show
+--------------+-----------+
| words| codes|
+--------------+-----------+
|[hello, world]|hello world|
+--------------+-----------+
使用 map 操作符可以完全控制应该转型什么以及如何转型.
Use map operator to have full control of what and how should be transformed.
map[U](func: (T) ⇒ U): Dataset[U] 返回一个新的 Dataset,其中包含将 func 应用于每个元素的结果.
map[U](func: (T) ⇒ U): Dataset[U] Returns a new Dataset that contains the result of applying func to each element.
scala> codes.show(false)
+---+---------------------------+
|id |rate_plan_code |
+---+---------------------------+
|0 |[AAA, RACK, SMOBIX, SMOBPX]|
+---+---------------------------+
val codesAsSingleString = codes.as[(Long, Array[String])]
.map { case (id, codes) => (id, codes.mkString(", ")) }
.toDF("id", "codes")
scala> codesAsSingleString.show(false)
+---+-------------------------+
|id |codes |
+---+-------------------------+
|0 |AAA, RACK, SMOBIX, SMOBPX|
+---+-------------------------+
scala> codesAsSingleString.printSchema
root
|-- id: long (nullable = false)
|-- codes: string (nullable = true)