[R] union of two sets are smaller than one set?

[Enrico Schumann]

On Sun, 31 Jan 2021, Martin Møller Skarbiniks Pedersen writes:

> This is really puzzling me and when I try to make a small example
> everything works like expected.
>
> The problem:
>
> I got these two large vectors of strings.
>
>> str(s1)
>  chr [1:766608] "0.dk" ...
>> str(s2)
>  chr [1:59387] "043.dk" "0606.dk" "0618.dk" "0888.dk" "0iq.dk" "0it.dk" ...
>
> And I need to create the union-set of s1 and s2.
> I expect the size of the union-set to be between 766608 and 766608+59387.
> However it is 681193 which is less that number of elements in s1!
>
>> length(base::union(s1, s2))
> [1] 681193
>
> Any hints?
>
> Regards
> Martin
>

Duplicates?

kind regards
    Enrico

-- 
Enrico Schumann
Lucerne, Switzerland
http://enricoschumann.net