Created
December 3, 2011 20:45
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キー毎に集計する例(irofさんの http://d.hatena.ne.jp/irof/20111203/p1 をScalaにしてみた)
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//getOrElseUpdateを使ってみたバージョン | |
case class Data(code: String, name: String, var value: Int) | |
val input = Seq( | |
Data("A01", "hoge", 100), Data("A01", "piyo", 200), | |
Data("A02", "hoge", 300), | |
Data("A03", "hoge", 400), Data("A03", "piyo", 500) | |
) | |
def summary1(list: Seq[Data]): Seq[Data] = { | |
val map = scala.collection.mutable.LinkedHashMap[String, Data]() | |
for (d <- list) { | |
val data = map.getOrElseUpdate(d.code, Data(d.code, "", 0)) | |
data.value += d.value | |
} | |
map.values.toList | |
} | |
summary1(input) |
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//Scalaのコレクションメソッドを駆使してみたバージョン | |
case class Data(code: String, name: String, value: Int) | |
val input = Seq( | |
Data("A01", "hoge", 100), Data("A01", "piyo", 200), | |
Data("A02", "hoge", 300), | |
Data("A03", "hoge", 400), Data("A03", "piyo", 500) | |
) | |
def summary2(list: Seq[Data]): Seq[Data] = { | |
list.groupBy(_.code).map{ case (code, data) => Data(code, "", data.map(_.value).sum) }.toSeq.sortBy(_.code) | |
} | |
summary2(input) |
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