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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' | ||
┌────┬──┐ | ┌────┬──┐ | ||
| Line 23: | Line 27: | ||
∊M | ∊M | ||
1 2 3 4 5 6 7 8 | 1 2 3 4 5 6 7 8 | ||
</ | </syntaxhighlight> | ||
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 | ||
| Line 42: | Line 46: | ||
⍴∊3 ⍝ It's now a vector | ⍴∊3 ⍝ It's now a vector | ||
1 | 1 | ||
</ | </syntaxhighlight> | ||
== External links == | == External links == | ||