Search code examples
rlistflatten

Flattening a list with unlist(), but keeping only the sublist names

I have a list in which each object is itself a list. I would like to flatten the list to one level, but keep the sublist names only, not prepend the higher level list name. I can use something like the example below, but I don't know how to keep only the sublist names?

# Create a list of lists
my_list <- list(
  group1 = list(a = 1, b = 2),
  group2 = list(c = 3, d = 4)
)

# Flatten
flat_list <- unlist(my_list, recursive = FALSE)

The result is:

> flat_list
$group1.a
[1] 1

$group1.b
[1] 2

$group2.c
[1] 3

$group2.d
[1] 4

But I don't want group1.a, I just want a.

Solution

  • Use unname() to drop the names of the top-level list, before unlist()ing.

    my_list |> 
  unname() |>
  unlist(FALSE)
#> $a
#> [1] 1
#> 
#> $b
#> [1] 2
#> 
#> $c
#> [1] 3
#> 
#> $d
#> [1] 4