How to combine the value of a column with same key in Scala?-CodePudding

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How to combine the value of a column with same key in Scala?

Time：07-05

Suppose I have this data

How can I join the value of Column B that has the same value in Column A? Example:

ColumnA	ColumnB
row1	valueA, valueB
row2	valueB

CodePudding user response：

You can use collect_set and concat_ws.

df.select("ColumnA","ColumnB")
  .groupBy("ColumnA")
  .agg(concat_ws(",",collect_set("ColumnB")))