I am trying to create an array object.

> a = array(NA, c(4,1,1))
> class(a)
[1] "array"
> a[1,1,1] = "test"
> class(a)
[1] "array"
> a[2,1,1] = list(1:5)
> class(a)
[1] "list"

I want the object a to stay as an array after getting a list as the value for a[2,1,1].

How can I do this?

Not a Bioconductor question, so probably better to ask on StackOverflow or similar. But create the array using list() rather than logical (NA).

> a = array(list(), c(4, 1, 1))
> a[2, 1, 1] = list(1:5)
> class(a)
[1] "array"
> typeof(a)
[1] "list"
> a
, , 1

     [,1]     
[1,] NULL     
[2,] Integer,5
[3,] NULL     
[4,] NULL     

> a[2, 1, 1]
[[1]]
[1] 1 2 3 4 5