detect empty lists in R

Question

i am calculating some values which are stored in a list and the list is appended to an alredy existing list, called results. In some cases the calculation returns TRUE. In that case i want to remove the element that returned TRUE from the list:

my_list
$`0`
[1] TRUE

$`1`
[1] TRUE


my_list = lapply(list(my_list), function(x){Filter(Negate(isTRUE), x)})
> my_list
[[1]]
named list()

This return an empty list. Now i want to check:

• if the list is empty - do nothing
• if the list is not empty append it to results

The problem is that when i check

length(my_list) >0
[1] TRUE

How can i detect if a list is empty?

Answer 1

We can use lengths to get the logical output for each list element

my_list[lengths(my_list) > 0]