Spark DataFrame按键将列值聚合到列表中 [英] Spark DataFrame aggregate column values by key into List

问题描述

我有一个看起来像这样的DataFrame:

I have a DataFrame that looks like this:

+-----------------+-------+
|Id               | value |
+-----------------+-------+
|             1622| 139685|
|             1622| 182118|
|             1622| 127955|
|             3837|3224815|
|             1622| 727761|
|             1622| 155875|
|             3837|1504923|
|             1622| 139684|
+-----------------+-------+

我想把它变成:

    +-----------------+-------------------------------------------+
    |Id               | value                                     |
    +-----------------+-------------------------------------------+
    |             1622|139685,182118,127955,727761,155875,139684  |
    |             3837|3224815,1504923                            |
    +-----------------+-------------------------------------------+

仅使用DataFrame函数可能吗?还是需要将其转换为和RDD?

Is this possible with DataFrame functions only or do I need to convert it to and RDD?

推荐答案

使用DataFrame API可能.试试:

It is possible with the DataFrame API. Try:

df.groupBy(col("Id"))
  .agg(collect_list(col("value")) as "value")

如果您要用,分隔的String而不是Array，请尝试以下操作:

If instead of an Array you want a String separated by ,, then try this:

df.groupBy(col("Id"))
  .agg(collect_list(col("value")) as "value")
  .withColumn("value", concat_ws(",", col("value")))

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