Replicate a list to create a list-of-lists

Question

I am trying to create a list with the following (nested) structure:

l <- list()
for(i in seq(5)) l[[i]] <- list(a=NA,b=NA)
> str(l)
List of 5
 $ :Li         


        

Answer 1

I think this has to do with rep behavior, you want to nest before you rep:

rep(list(fred),5)

The str output:

List of 5
 $ :List of 2
  ..$ happy: int [1:10] 1 2 3 4 5 6 7 8 9 10
  ..$ name : chr "squash"
 $ :List of 2
  ..$ happy: int [1:10] 1 2 3 4 5 6 7 8 9 10
  ..$ name : chr "squash"
 $ :List of 2
  ..$ happy: int [1:10] 1 2 3 4 5 6 7 8 9 10
  ..$ name : chr "squash"
 $ :List of 2
  ..$ happy: int [1:10] 1 2 3 4 5 6 7 8 9 10
  ..$ name : chr "squash"
 $ :List of 2
  ..$ happy: int [1:10] 1 2 3 4 5 6 7 8 9 10
  ..$ name : chr "squash"

Answer 2

You can use replicate:

l <- replicate(5, list(a=NA,b=NA), simplify=FALSE)