How to take every second element

Question

If I have {1,2,3,4,5,6}, how do I take all the second elements into a new list? So I want a list like {2,4,6}.

list={1,2,3,4,5,6}; list[[2;; ;;2]]. Extract[list, Range[2,Length@list,2]. Partition[list, 2][[All, 2]]. Etc. — march, Oct 29 '15 at 06:46
If you search the docs for "take every second element", the first hit is Take, which is the function. If you use the free-form input to "take every second element from list", you get %[[1 ;; -1 ;; 2]], which is easily adapted. — Patrick Stevens, Oct 29 '15 at 07:06
The function that march and Patrick are referring to is Span, just type ?Span into your notebook to get the information on how to use it. — Jason B., Oct 29 '15 at 07:35
Guy, we should re-open this question, and make it a canonical version. Then mark this one as a duplicate. This might not be that easy to find for a beginner actually ... — Szabolcs, Oct 29 '15 at 08:40

score 5 · Answer 1 · answered Oct 29 '15 at 08:37

5

The keywords are Part ([[ ... ]]) and Span (;;).

Simply use

list[[2;; ;; 2]]

answered Oct 29 '15 at 08:37

Szabolcs

1 Answers1