Top "Seq" questions

Add an index (or counter) to a dataframe by group in R

I have a df like ProjectID Dist 1 x 1 y 2 z 2 x 2 h 3 k .... .... I want to add a third column …

r indexing counter plyr seq

what's the difference between Seq and Set in Scala

var seq = Seq[String]() seq = seq :+ "hello" var set = Set[String]() set += "hello" what's the difference between Seq and Set?

scala set seq