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Promote: Difference between revisions
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(Created page with "'''Promote''' is a monadic function that adds a length-1 axis to its argument before the other axes, resulting in an array with rank one higher. It appears as a primitive in Kap (<syntaxhighlight lang=apl inline><</syntaxhighlight>, "increase rank") and Dyalog APL Vision (<syntaxhighlight lang=apl inline>∧</syntaxhighlight>), as well as J (<syntaxhighlight lang=j inline>,:</syntaxhighlight>, "'''Itemize'''"), BQN (<code>≍</code>, "...") |
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'''Promote''' is a [[monadic]] [[function]] that adds a length-1 [[axis]] to its argument before the other axes, resulting in an array with [[rank]] one higher. It appears as a [[primitive]] in [[Kap]] (<syntaxhighlight lang=apl inline><</syntaxhighlight>, "increase rank") and [[Dyalog APL Vision]] (<syntaxhighlight lang=apl inline>∧</syntaxhighlight>), as well as [[J]] (<syntaxhighlight lang=j inline>,:</syntaxhighlight>, "'''Itemize'''"), [[BQN]] (<code>≍</code>, "'''Solo'''"), and [[Uiua]] (<code>¤</code>, "'''Fix'''"). In J and BQN it's paired with the related dyadic primitive [[Laminate]]. The [[K]] primitive Enlist (<code>,</code>), which creates a length-1 list containing its argument, can also be interpreted as Promote because [[depth]] and rank are equivalent in the [[list model]] of arrays. | '''Promote''' is a [[monadic]] [[function]] that adds a length-1 [[axis]] to its argument before the other axes, resulting in an array with [[rank]] one higher. It appears as a [[primitive]] in [[Kap]] (<syntaxhighlight lang=apl inline><</syntaxhighlight>, "increase rank") and [[Dyalog APL Vision]] (<syntaxhighlight lang=apl inline>∧</syntaxhighlight>), as well as [[J]] (<syntaxhighlight lang=j inline>,:</syntaxhighlight>, "'''Itemize'''"), [[BQN]] (<code>≍</code>, "'''Solo'''"), and [[Uiua]] (<code>¤</code>, "'''Fix'''"). In J and BQN it's paired with the related dyadic primitive [[Laminate]]. The [[K]] primitive Enlist (<code>,</code>), which creates a length-1 list containing its argument, can also be interpreted as Promote because [[depth]] and rank are equivalent in the [[list model]] of arrays. | ||
For an argument <syntaxhighlight lang=apl inline>A</syntaxhighlight>, promote can be implemented as <syntaxhighlight lang=apl inline>(1,⍴A) ⍴ A</syntaxhighlight> or <syntaxhighlight lang=apl inline>(⍳1) ∘.⊢ A</syntaxhighlight>. The choice to add an axis at the beginning is based on [[leading axis theory]], as this allows the axis to be placed in any other position using the [[Rank operator]]. | For an argument <syntaxhighlight lang=apl inline>A</syntaxhighlight>, promote can be implemented with [[Ravel]] with [[Function axis|axis]] as <syntaxhighlight lang=apl inline>,[⎕IO-0.5] A</syntaxhighlight>, with [[Reshape]] as <syntaxhighlight lang=apl inline>(1,⍴A) ⍴ A</syntaxhighlight>, or with [[Outer Product]] as <syntaxhighlight lang=apl inline>(⍳1) ∘.⊢ A</syntaxhighlight>. The choice to add an axis at the beginning is based on [[leading axis theory]], as this allows the axis to be placed in any other position using the [[Rank operator]]. | ||
== Documentation == | == Documentation == | ||