[英]scala: foldLeft with zipWithIndex
以下代碼有效 :
likertRoundDfSeq:Seq[DataFrame] = ......
likertRoundDfSeq match
{
case head :: tail => tail.foldLeft(head){(dforg,df1)=>
DataFrameUtils.join(dforg,devianceFromAverageOneRound(df1),"A_RowId")
}
}
但是,我需要將索引添加為devianceFromAverageOneRound
的附加參數
我想用zipWithIndex
做到這一點,也許是這樣的:
likertRoundDfSeq match
{
case head :: tail => tail.zipWithIndex.foldLeft(head){(dforg,df1)=>
DataFrameUtils.join(dforg,devianceFromAverageOneRound(df1,*myzipindex*),"A_RowId" )
}
}
但是我不確定在這種情況下如何分解數據幀和idx。 Intellij似乎不指導我,所以我有點迷路
任何意見,將不勝感激
現在,DF Seq的尾部是Tuple2 [DataFrame,Long]的列表,因此, foldLeft
應該如下所示:
case head :: tail => tail.zipWithIndex.foldLeft(head){ (dforg, df1) =>
DataFrameUtils.join(dforg, devianceFromAverageOneRound(df1._1, df1._2), "A_RowId")
假設您的新的devianceFromAverageOneRound(DataFrame, Long)
仍返回一個DataFrame
(而不是Tuple2[DataFrame, Long]
)。
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