↓ — Split / Drop

Function. Keys: Alt-j. Ranks: 1 monadic, 1 ∞ dyadic

↓Y nests vectors along the last axis.

↓2 3⍴⍳6            ⍝ [[0 1 2] [3 4 5]]

N↓Y drops from the front; negative N drops from the end.

2↓1 2 3 4          ⍝ 3 4
¯2↓1 2 3 4         ⍝ 1 2

With axes, ⍠K selects the split axis or the drop axes.

↓⍠0 (2 3⍴⍳6)       ⍝ [[0 3] [1 4] [2 5]]

Vector counts apply to successive leading axes. Overdrop gives an empty axis.

1 1↓2 3⍴⍳6         ⍝ [4 5⋄]
5↓1 2              ⍝ ⍬

See Mix / Take.

Inverse

↓⁻¹Y mixes the items of Y into one array.

↓⁻¹[1 2;3 4]   ⍝ [1 2⋄3 4]