Filter values from list in R

Question

I want to calculate the mean of a list of named numbers. There are numeric(0) values that I first want to remove. Also, I would like to retrieve which elements of

Answer 1

Another solution using the Filter function from base R:

mean(unlist(Filter(is.numeric, l)))

Answer 2

Unlisting will pull out just the numeric entries in a single vector which you can call mean on, so try:

mean(unlist(r["gg",]))

Answer 3

## Example list

l <- list(n1=numeric(0), n2="foo", n3=numeric(0), n4=1:5)

## Filter out elements with length 0

l[lapply(l, length) > 0]


$n2
[1] "foo"

$n4
[1] 1 2 3 4 5


## Get names of elements with length 0

names(l)[lapply(l, length) == 0]

[1] "n1" "n3"