Create a variable that identifies the original data.frame after rbind command in R

Question

I am relatively new to R and I would like to know how can I create a variable (number sequence) that identifies the each of the original data.frames before being joined with

Answer 1

Thanks all! I ended up with a simple solution working with a friend of mine by creating an index, like this:

index<-rep(1,times=nrow(data.frame))

for (i in 1:(nrow(data.frame)-1)){

if (data_frame$ID [i+1]<= data.frame$ID[i]) {
index[i+1]<-index[i]+1
}
else {index[i+1]<-index[i]}}

new.data.frame <- cbind(index, data.frame)