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?
EDIT- I will show an example of what does not work for me:
list1 <- list()
list1[1] = 1
list1[2] = 2
list2 <- list()
list2[1] = 'a'
list2[2] = 'b'
list_all <- list(list1, list2)
a = list_all[1]
a[2]
#[[1]]
#NULL
but a
should be a list!
This question is related to
r
As other answers pointed out in a more complicated way already, you did already create a list of lists! It's just the odd output of R that confuses (everybody?). Try this:
> str(list_all)
List of 2
$ :List of 2
..$ : num 1
..$ : num 2
$ :List of 2
..$ : chr "a"
..$ : chr "b"
And the most simple construction would be this:
> str(list(list(1, 2), list("a", "b")))
List of 2
$ :List of 2
..$ : num 1
..$ : num 2
$ :List of 2
..$ : chr "a"
..$ : chr "b"
The example creates a list of named lists in a loop.
MyList <- list()
for (aName in c("name1", "name2")){
MyList[[aName]] <- list(aName)
}
MyList[["name1"]]
MyList[["name2"]]
To add another list named "name3" do write:
MyList$name3 <- list(1, 2, 3)
Using your example::
list1 <- list()
list1[1] = 1
list1[2] = 2
list2 <- list()
list2[1] = 'a'
list2[2] = 'b'
list_all <- list(list1, list2)
Use '[[' to retrieve an element of a list:
b = list_all[[1]]
b
[[1]]
[1] 1
[[2]]
[1] 2
class(b)
[1] "list"
If you are trying to keep a list
of list
s (similar to python
's list.append()
) then this might work:
a <- list(1,2,3)
b <- list(4,5,6)
c <- append(list(a), list(b))
> c
[[1]]
[[1]][[1]]
[1] 1
[[1]][[2]]
[1] 2
[[1]][[3]]
[1] 3
[[2]]
[[2]][[1]]
[1] 4
[[2]][[2]]
[1] 5
[[2]][[3]]
[1] 6
Source: Stackoverflow.com