paste, by and data.table in r

Question

I\'m trying to paste strings from a reshaped dataset. I\'m using the data.table package as follows:

m<-data.frame(x=rep(c(\"a\",\"b\"),20),y=factor(sample         


        

Answer 1

For completeness' sake, an official answer:

If you use paste(y,collapse=",") instead, it should work.