title: How can I make a list of lists in R?
body: <p>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?</p>
  
  <p><strong>EDIT-</strong> I will show an example of what does not work for me:</p>
  
  <pre><code>list1 &lt;- list()
  list1[1] = 1
  list1[2] = 2
  list2 &lt;- list()
  list2[1] = 'a'
  list2[2] = 'b'
  list_all &lt;- list(list1, list2)
  a = list_all[1]
  a[2]
  #[[1]]
  #NULL
  </code></pre>
  
  <p>but <code>a</code> should be a list!</p>