How can I make a list of lists in R?

Question

I don't know how to make a list of lists in R. I have several lists, I want to store them in one data structure to make accessing them easier. However, it looks like you cannot use a list of lists in R, so if I get list l1 from another list, say, l2 then I cannot access elements l1. How can I implement it?

EDIT- I will show an example of what does not work for me:

list1 <- list() list1[1] = 1 list1[2] = 2 list2 <- list() list2[1] = 'a' list2[2] = 'b' list_all <- list(list1, list2) a = list_all[1] a[2] #[[1]] #NULL 

but a should be a list!

Answer 1

You can easily make lists of lists

list1 <- list(a = 2, b = 3) list2 <- list(c = "a", d = "b") mylist <- list(list1, list2) 

mylist is now a list that contains two lists. To access list1 you can use mylist[[1]]. If you want to be able to something like mylist$list1 then you need to do somethingl like

mylist <- list(list1 = list1, list2 = list2) # Now you can do the following mylist$list1 

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Edit: To reply to your edit. Just use double bracket indexing

a <- list_all[[1]] a[[1]] #[1] 1 a[[2]] #[1] 2 

Answer 2

Using your example::

list1 <- list() list1[1] = 1 list1[2] = 2 list2 <- list() list2[1] = 'a' list2[2] = 'b' list_all <- list(list1, list2) 

Use '[[' to retrieve an element of a list:

b = list_all[[1]]  b [[1]] [1] 1  [[2]] [1] 2  class(b) [1] "list"