Remove NULL and reduce one level of listing in R

Asked Oct 29 '19 at 16:14

Active Oct 29 '19 at 16:14

Viewed 43 times

In list A below, I was wondering how to remove any NULL and exactly get my desired output shown below? (my instinct says do.call() can help!)

A <- list(X = NULL, Y = list(a = matrix(1:2), b = matrix(3:4)))

# I tried the following without success:
lapply(seq_along(A), function(i) Filter(Negate(is.null), A[[i]]))

# DESIRED OUTPUT:

# [[1]]$`a`
#      [,1]
# [1,]    1
# [2,]    2

# [[2]]$b
#     [,1]
# [1,]   3
# [2,]   4

asked Oct 29 '19 at 16:14

1

See here how to get non-null list elements: https://stackoverflow.com/questions/16896376/extract-non-null-elements-from-a-list-in-r – Mario Oct 29 '19 at 16:18
2

`A[!sapply(A, is.null)]` is much simpler. – Rui Barradas Oct 29 '19 at 16:18

Remove NULL and reduce one level of listing in R

0 Answers0