Spark Scala将数据框架中的每个组与其他参考数据框架连接起来

Question

I have the following two data frames. I want do group by on input data frame and join each group with reference data frame on date column.

   %>input.show()

  sid|date                 |count
  200|2016-04-30 18:00     | 10
  100|2016-04-30 18:00     | 2
  200 |2016-04-30 21:00    | 5
  100|2016-04-30 21:00     | 4

    %>reference.show()
   id|date           
   1|2016-04-30 18:00  
   2|2016-04-30 21:00  

   expected output
   id|sid|date             |count
   1|200|2016-04-30 18:00  |10
   2|200|2016-04-30 21:00  |5
   1|100|2016-04-30 18:00  |2
   2|100|2016-04-30 21:00  |4

Answer 1

普通加入：

reference.join(input, Array("date"))