Add data frames row wise with [d]plyr

Question

I have two data frames

df1
#    a  b
# 1 10 20
# 2 11 21
# 3 12 22
# 4 13 23
# 5 14 24
# 6 15 25

df2
#   a b
# 1 4 8

I want the following output:

df3
#    a  b
# 1 14 28
# 2 15 29
# 3 16 30
# 4 17 31
# 5 18 32
# 6 19 33

i.e. add df2 to each row of df1.

Is there a way to get the desired output using plyr (mdplyr??) or dplyr?

Answer 1

I see no reason for "dplyr" for something like this. In base R you could just do:

df1 + unclass(df2)
#    a  b
# 1 14 28
# 2 15 29
# 3 16 30
# 4 17 31
# 5 18 32
# 6 19 33

Which is the same as df1 + list(4, 8).

Answer 2

One liner with dplyr.

mutate_each(df1, funs(.+ df2$.), a:b)

#   a  b
#1 14 28
#2 15 29
#3 16 30
#4 17 31
#5 18 32
#6 19 33