How to combine rows based on unique values in R? [duplicate]

Answer 1

You can try

library(data.table)
setDT(df1)[, list(Values=paste(Values, collapse=",")) ,ID]

Or using base R

 aggregate(.~ID, df1, paste, collapse=",")

Answer 2

dat <- read.table(text="ID  Values
820 D1,D2,FE
730 D1,D2,D3,PC,Io,He,Bt,Te,AR,PG
730 DV,GTH,LYT
567 EDR,TYU,EOP,OMN
567 FGH,KIH,IOP", header=TRUE)

dat2 <- dat %>% group_by(ID) %>% summarise(val=paste(Values, collapse=","))