scala中 _ reduce groupByKey reduceByKey...用法記錄

1: 若是變量是List的話，_ 就至關於List變量每個元素python scala> List((1,2),(5,9)).filter(_._1>1) res5: List[(Int, Int)] = List((5,9)) scala> List((1,2),(5,9)).filter(_._2>1) res6: List[(Int, Int)] = List((1,2), (5,9))

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