[R] How to create a list that grows automatically

[hadley wickham]

> I would like to know if there is a way to create a list or an array (or
> anything) which grows automatically as more elements are put into it. What I
> want to find is something equivalent to an ArrayList object of Java
> language. In Java, I can do the following thing:
>
> // Java code
> ArrayList myArray = new ArrayList();
> myArray.add("object1");
> myArray.add("object2");
> ....
> // End of java code

As others have mentioned, you can do this with lists in R.

However, there is an important difference between ArrayLists in Java
and Lists in R.  In Java, when an ArrayList grows past its bound, it
doesn't allocate just enough space, it allocates a lot more, so the
next time you allocate past the end of the array, there's space
already reserved.  This gives (IIRC) amortised O(n) behaviour.  R
doesn't do this however, so has to copy the entire array every time
giving O(n^2) behaviour.

Hadley