Same function over multiple data frames in R

Question

I am new to R, and this is a very simple question. I\'ve found a lot of similar things to what I want but not exactly it. Basically I have multiple data frames and I simply

Answer 1

Put them into a list and then run rowMeans over the list.

df1 <- data.frame(x = rep(3, 5), y = seq(1, 5, 1), ID = letters[1:5])
df2 <- data.frame(x = rep(5, 5), y = seq(2, 6, 1), ID = letters[6:10])

lapply(list(df1, df2), function(w) { w$Avg <- rowMeans(w[1:2]); w })

 [[1]]
   x y ID Avg
 1 3 1  a 2.0
 2 3 2  b 2.5
 3 3 3  c 3.0
 4 3 4  d 3.5
 5 3 5  e 4.0

 [[2]]
   x y ID Avg
 1 5 2  f 3.5
 2 5 3  g 4.0
 3 5 4  h 4.5
 4 5 5  i 5.0
 5 5 6  j 5.5