数组x的索引n处的项目值的惯用J

Question

In the J language, what is the idiomatic word or phrase to return the value of the item at index n of array x? The documentation for {:: seems concerned with boxed values, mentioning normal arrays as an afterthought.

    nth =: {:: NB. This is what I have found, but is there a better word?
    2 nth 5 12 73 23 89
73
    1 nth 3 3 $ i.9
3 4 5

Answer 1

You are looking for from ( { ). It returns item(s) from an array

   2 { 5 12 73 23 89
73
   2 4 { 5 12 73 23 89
73 89
   2 { i. 4 5
10 11 12 13 14

Some references for from :

• Vocabulary on Jwiki
• J Dictionary