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

A solution from purrr, which uses map_dfc to loop through all columns in df1 to combine all the elements with df2$A.

library(purrr)

map_dfc(df1, ~c(., df2$A))

# A tibble: 6 x 3
      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

Data

df1 <- 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))

df2 <- structure(list(A = 1:4), .Names = "A", class = "data.frame",
                 row.names = c(NA, -4L))