How to append group row into dataframe

Question

I have this df1:

A B C
1 2 3
5 7 9

where A B C are columns names.

I have another df2 with one column:

A
1
         


        

Answer 1

Here is a base R method with rbind, rep, and setNames:

rbind(dat, setNames(data.frame(rep(dat1, ncol(dat))), names(dat)))
  A B C
1 1 2 3
2 5 7 9
3 1 1 1
4 2 2 2
5 3 3 3
6 4 4 4

Edit: turns outdata.frame isn't necessary:

rbind(dat, setNames(rep(dat1, ncol(dat)), names(dat)))

will work.

data

dat <- 
structure(list(A = c(1L, 5L), B = c(2L, 7L), C = c(3L, 9L)), .Names = c("A", 
"B", "C"), class = "data.frame", row.names = c(NA, -2L))

dat1 <-
structure(list(A = 1:4), .Names = "A", row.names = c(NA, -4L),
class = "data.frame")