Create list of lists in R

Question

I am new in R and I have a task to create list of lists.
I tried this:

newl <- list()
newl <- append(newl, list(a = 1, b = "x"))
newl <- append(newl, list(a = 15, b = "y"))
newl <- append(newl, list(a = 10, b = "z"))

But append works like extend Python function:

$a
[1] 1

$b
[1] "x"

$a
[1] 15

$b
[1] "y"

$a
[1] 10

$b
[1] "z"

I want to get something like this:

[[1]]
$a
[1] 1
$b 
[1] "x"

[[2]]
$a
[1] 15
$b
[1] "y"

[[3]]
$a
[1] 10
$b
[1] "z"

Also I want to have an opportunity to sort elements of my list of lists by parameter (for example, by a ). It would look like this:

[[1]]
$a
[1] 1
$b 
[1] "x"

[[2]]
$a 
[1] 10
$b 
[1] "z"

[[3]]
$a 
[1] 15
$b 
[1] "y"

Also it's important for me to have elements different types inside lists ( int and string in the example). In real task it would be function , vector , double and matrix .

Maybe I need to choose another data type to solve my problem?

Answer 1

Actually you are already close to your desired output, but you may need another list() within append , eg,

newl <- list()
newl <- append(newl, list(list(a = 1, b = "x")))
newl <- append(newl, list(list(a = 15, b = "y")))
newl <- append(newl, list(list(a = 10, b = "z")))

such that

> newl
[[1]]
[[1]]$a
[1] 1

[[1]]$b
[1] "x"


[[2]]
[[2]]$a
[1] 15

[[2]]$b
[1] "y"


[[3]]
[[3]]$a
[1] 10

[[3]]$b
[1] "z"

---

If you want to sort by $a , you can try

> newl[order(sapply(newl, `[[`, "a"))]
[[1]]
[[1]]$a
[1] 1

[[1]]$b
[1] "x"


[[2]]
[[2]]$a
[1] 10

[[2]]$b
[1] "z"


[[3]]
[[3]]$a
[1] 15

[[3]]$b
[1] "y"

Answer 2

We could do a split

lst1 <- unname(split(newl, as.integer(gl(length(newl), 2, length(newl)))))