Select first element of nested list

Question

Let\'s say I have a list like this:

x = list(list(1,2), list(3,4), list(5,6))

I would like a list that contains only the first elements of

Answer 1

Not exactly a short notation, but this can also be done with a fold:

Reduce(function(a, b) c(a, b[1]), x, init = c()) 

# [[1]]
# [1] 1
# 
# [[2]]
# [1] 3
# 
# [[3]]
# [1] 5