Enlist: Difference between revisions
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:''For the K and BQN function that creates a one-element list containing its argument, see [[Pair]].'' | |||
{{Built-in|Enlist|∊}} is a [[primitive function]] which returns a [[simple]] [[vector]] of all simple [[scalar]] values in a possibly [[nested array]]. Enlist differs from [[Ravel]] in that Enlist flattens over all layers of nesting, while Ravel flattens only the outermost layer. Enlist shares its [[glyph]] <syntaxhighlight lang=apl inline>∊</syntaxhighlight> with the dyadic function [[Membership]]. | {{Built-in|Enlist|∊}} is a [[primitive function]] which returns a [[simple]] [[vector]] of all simple [[scalar]] values in a possibly [[nested array]]. Enlist differs from [[Ravel]] in that Enlist flattens over all layers of nesting, while Ravel flattens only the outermost layer. Enlist shares its [[glyph]] <syntaxhighlight lang=apl inline>∊</syntaxhighlight> with the dyadic function [[Membership]]. | ||
== Support == | == Support == | ||
Latest revision as of 15:32, 6 March 2024
- For the K and BQN function that creates a one-element list containing its argument, see Pair.
∊
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Enlist (∊) is a primitive function which returns a simple vector of all simple scalar values in a possibly nested array. Enlist differs from Ravel in that Enlist flattens over all layers of nesting, while Ravel flattens only the outermost layer. Enlist shares its glyph ∊ with the dyadic function Membership.
Support
APL2 IUP had ∊ mean Type[1] and Dyalog APL originally did too. However, by the time IBM released APL2, ∊ (which stood for e in prototypical element) was repurposed for Enlist (∊ being for e in enlist). Thus, Dyalog left the Type meaning in place only when migration level is 0, while setting it to 1 (the default) or higher follows IBM's replacement meaning.
Examples
Enlist is equivalent to a depth-first search collecting all simple scalars, where each layer (which in turn can be of any rank) is traversed in ravel order.
⎕←MAT←2 2⍴'MISS' 'IS' 'SIP' 'PI'
┌────┬──┐
│MISS│IS│
├────┼──┤
│SIP │PI│
└────┴──┘
∊MAT
MISSISSIPPI
⎕←M←1 (2 2⍴2 3 4 5) (6(7 8))
┌─┬───┬───────┐
│1│2 3│┌─┬───┐│
│ │4 5││6│7 8││
│ │ │└─┴───┘│
└─┴───┴───────┘
∊M
1 2 3 4 5 6 7 8
Enlist acts like Ravel for simple arrays. This includes simple scalars, where the result is a singleton vector.
⎕←mat←4 4⍴⍳16
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
(,mat)≡∊mat
1
∊3
3
3 ≡ ∊3 ⍝ Not the same
0
⍴∊3 ⍝ It's now a vector
1
External links
Lessons
Documentation