how to use groupby method ?

Question

how to use groupby method ?

Closed this issue a year ago · 2 comments

HI ,when I create the Frame[Int,int,string] by saddle ,I want to compute one field column every element count, like

frame.columnAt(index).groupby( ele => ele.count), but I found can not coding like this, how to do it,thanks

Answer 1 · 2023-01-01T07:59:07.000Z

also I can use origin scala method like this

   val dataCsvOpt =csv.CsvParser.parseFromIterator[String](charBufferIter,fieldSeparator='\t',recordSeparator = "\n").toOption
 val dataCsv = dataCsvOpt.get._1
val maiArr= dataCsv.colAt(27).values.map(el =>(el,1)).toArray.groupBy(el =>el._1).mapValues(el => el.map(_._2).sum).toList.sortBy(_._2).reverse

Answer 2 · 2023-05-14T07:43:27.000Z

Hi, sorry for the late answer.

Frame's groupby always operates on row index.
However you can provide a custom index for the group by https://pityka.github.io/saddle/api/org/saddle/Frame.html#groupBy[Y](fn:RX=%3EY)(implicitevidence$35:org.saddle.ST[Y],implicitevidence$36:org.saddle.ORD[Y]):org.saddle.groupby.FrameGrouper[Y,RX,CX,T]