R – Concatenate two dataframes?

You want “rbind”.

b$b <- NA
new <- rbind(a, b)

rbind requires the data frames to have the same columns.

The first line adds column b to data frame b.

Results

> a <- data.frame(a=c(0,1,2), b=c(3,4,5), c=c(6,7,8))
> a
  a b c
1 0 3 6
2 1 4 7
3 2 5 8
> b <- data.frame(a=c(9,10,11), c=c(12,13,14))
> b
   a  c
1  9 12
2 10 13
3 11 14
> b$b <- NA
> b
   a  c  b
1  9 12 NA
2 10 13 NA
3 11 14 NA
> new <- rbind(a,b)
> new
   a  b  c
1  0  3  6
2  1  4  7
3  2  5  8
4  9 NA 12
5 10 NA 13
6 11 NA 14