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

Why not just:

    rbind( cbind(df1, origin="df1"),
           cbind(df2,  origin='df2') )

Or if you want to preserve rownames:

  rbind( cbind(df1, origin=paste("df1",rownames(df1), sep="_") ),
         cbind(df2, origin=paste("df1",rownames(df1), sep="_") ) )