How to avoid unlist() modification of list naming

Question

I am a bit puzzled by the names produced by unlist(). Please consider the following MWE

vector1 <- c(1,2,3,4,5,6,7,8,9,10)
names(vector1) <- c(1,2,2,3,4,4,5,6,6,6)
names(vector1)
# [1] "1" "2" "2" "3" "4" "4" "5" "6" "6" "6"
list1 <- split(vector1,names(vector1))
names(list1)
# [1] "1" "2" "3" "4" "5" "6"

but then

names(unlist(list1))
# [1] "1.1" "2.2" "2.2" "3.3" "4.4" "4.4" "5.5" "6.6" "6.6" "6.6"

According to the documentation of unlist()

By default, unlist tries to retain the naming information present in x.

so I can't make sense of this particular behaviour.

My problem is that the names as created by unlist() can't be matched against the names of the original vector1.

Answer 1

unlist(unname(list1))
#  1  2  2  3  4  4  5  6  6  6 
#  1  2  3  4  5  6  7  8  9 10 

Answer 2

I sympathize with your frustration. R is (I think) trying to retain both the information in names(x) and the information in the names of the original components (consider the results of unlist(setNames(list1,letters[1:6])), which makes the behaviour make more sense).

You can get what you want via

setNames(unlist(list1),unlist(lapply(list1,names)))

although it is admittedly awkward -- I would make this into an unlistWithNames function (or something sensibly named) if I wanted to do it often. PS @JoshOBrien's answer is simpler, but I will leave this here because it explains things a bit more.