Enlist: Difference between revisions
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{{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]] < | :''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]]. | |||
== Support == | |||
[[APL2]] IUP had <syntaxhighlight lang=apl inline>∊</syntaxhighlight> mean [[Type]]<ref>Graham, Alan. [https://dl.acm.org/doi/pdf/10.1145/22008.22033#page=4 Idioms and Problem Solving Techniques in APL2; Appendix - APL2 Idiom List: 9. Type]. [[APL86]].</ref> and [[Dyalog APL]] originally did too. However, by the time [[IBM]] released APL2, <syntaxhighlight lang=apl inline>∊</syntaxhighlight> (which stood for '''''e''''' in ''prototypical '''e'''lement'') was repurposed for [[Enlist]] (<syntaxhighlight lang=apl inline>∊</syntaxhighlight> being for '''''e''''' in '''''e'''nlist''). 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 == | == Examples == | ||
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Enlist is equivalent to a [[wikipedia:depth-first search|depth-first search]] collecting all simple scalars, where each layer (which in turn can be of any rank) is traversed in [[ravel order]]. | Enlist is equivalent to a [[wikipedia:depth-first search|depth-first search]] collecting all simple scalars, where each layer (which in turn can be of any rank) is traversed in [[ravel order]]. | ||
< | <syntaxhighlight lang=apl> | ||
⎕←MAT←2 2⍴'MISS' 'IS' 'SIP' 'PI' | ⎕←MAT←2 2⍴'MISS' 'IS' 'SIP' 'PI' | ||
┌────┬──┐ | ┌────┬──┐ | ||
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Enlist acts like [[Ravel]] for simple arrays. This includes simple scalars, where the result is a [[singleton]] vector. | Enlist acts like [[Ravel]] for simple arrays. This includes simple scalars, where the result is a [[singleton]] vector. | ||
< | <syntaxhighlight lang=apl> | ||
⎕←mat←4 4⍴⍳16 | ⎕←mat←4 4⍴⍳16 | ||
1 2 3 4 | 1 2 3 4 | ||
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.
∊
|
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