[R] flatten a list of lists

[Ista Zahn]

unlist(mfoo, recursive = FALSE) gets you pretty close.

Best,
Ista

On Thu, Oct 17, 2013 at 9:15 AM, Michael Friendly <friendly at yorku.ca> wrote:
> I have functions that generate lists objects of class "foo" and lists of
> lists of these, of class
> "foolist", similar to what is shown below.
>
> How can I flatten something like this to remove the top-level list
> structure, i.e.,
> return a single-level list of "foo" objects, of class "foolist"?
>
> foo <- function(n) {
>     result <- list(x=sample(1:10,n), y=sample(1:10,n))
>     class(result) <- "foo"
>     result
> }
>
> multifoo <- function(vec, label, ...) {
>     result <- lapply(vec, foo, ...)
>     names(result) <- paste0(label, vec)
>     class(result) <- "foolist"
>     result
> }
>
> foo1 <- multifoo(1:2, "A")
> foo2 <- multifoo(1:2, "B")
>
> mfoo <- list(A=foo1, B=foo2)
>
> str(mfoo, 2)
>
>> str(mfoo, 2)
> List of 2
>  $ A:List of 2
>   ..$ A1:List of 2
>   .. ..- attr(*, "class")= chr "foo"
>   ..$ A2:List of 2
>   .. ..- attr(*, "class")= chr "foo"
>   ..- attr(*, "class")= chr "foolist"
>  $ B:List of 2
>   ..$ B1:List of 2
>   .. ..- attr(*, "class")= chr "foo"
>   ..$ B2:List of 2
>   .. ..- attr(*, "class")= chr "foo"
>   ..- attr(*, "class")= chr "foolist"
>
> In this case, what is wanted is a single-level list, of 4 foo objects, A1,
> A2, B1, B2,
> all of class "foolist"
>
> --
> Michael Friendly     Email: friendly AT yorku DOT ca
> Professor, Psychology Dept. & Chair, Quantitative Methods
> York University      Voice: 416 736-2100 x66249 Fax: 416 736-5814
> 4700 Keele Street    Web:   http://www.datavis.ca
> Toronto, ONT  M3J 1P3 CANADA
>
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