R - Merge two data frames with one differing column

Question

Suppose I have two data frames

df1 = data.frame(id = c(1,1,1), stat = c("B", "A", "C"), value = c(10,11,12))
df2 = data.frame(id = c(2,2,2), stat = c("B", "A", "C"), value = c(20,21, 22))

Basically the first column identifies the data frame, the second column is some statistic I want to keep track of and the last column is the value of that statistics. Can I easily merge the data frames so that I get

stat  id    value
B     1     10
B     2     20    
A     1     11
A     2     21
C     1     12
C     2     22

I'd like to preserve the order of the stat column even though it's not alphabetical

Answer 1

You could do

(r <- rbind(df1, df2))[c(2,1,3)][order(r$stat, decreasing = TRUE),]
#   stat id value
# 1    B  1    10
# 3    B  2    20
# 2    A  1    11
# 4    A  2    21

In response to the edited question, you could use

f <- function(i) rbind(df1[i,], df2[i,])
do.call(rbind, lapply(1:nrow(df1), f))[c(2,1,3)]
#    stat id value
# 1     B  1    10
# 2     B  2    20
# 22    A  1    11
# 21    A  2    21
# 3     C  1    12
# 31    C  2    22