lapply function /loops on list of lists R

Question

I know this topic appeared on SO a few times, but the examples were often more complicated and I would like to have an answer (or set of possible solutions) to this simple situa

Answer 1

We can loop through the list of list with a nested lapply/sapply

 lapply(data, sapply, mean)

It is otherwise written as

 lapply(data, function(x) sapply(x, mean))

Or if you need the output with the list structure, a nested lapply can be used

 lapply(data, lapply, mean)

Or with rapply, we can use the argument how to get what kind of output we want.

  rapply(data, mean, how='list')

If we are using a for loop, we may need to create an object to store the results.

  res <- vector('list', length(data))
  for(i in seq_along(data)){
    for(j in seq_along(data[[i]])){
      res[[i]][[j]] <- mean(data[[i]][[j]])
    }
   }