Pair

From APL Wiki
Revision as of 22:24, 10 September 2022 by Adám Brudzewsky (talk | contribs) (Text replacement - "<source" to "<syntaxhighlight")
Jump to navigation Jump to search

Pair () or Juxtapose is a primitive function equivalent to the dfn {⍺←,⊂ ⋄ ⍺ ⍵} which aids in constructing nested arrays during tacit programming where stranding by juxtaposition is not available. It is also equivalent to the catenation of the enclosed arguments; ,⍥⊂ using the Over operator[1] or ,⍨∘⊂⍨∘⊂ using only the traditional operators Commute and Compose. It was introduced in Extended Dyalog APL, and then adopted into dzaima/APL.

Common usage

Its plain usage is in pairing up two parallel values:

Try it online!

      6 7 8(+⍮-)3
┌───────┬─────┐
│9 10 11│3 4 5│
└───────┴─────┘

It can also be combined with Mix to increase rank rather than depth:

Try it online!

      6 7 8(+↑⍤⍮-)3
9 10 11
3  4  5

See also

References

  1. "Composition and Enclosure" § Composition Operators. SATN-41, 1981-06-20.
APL built-ins [edit]
Primitives (Timeline) Functions
Scalar
Monadic ConjugateNegateSignumReciprocalMagnitudeExponentialNatural LogarithmFloorCeilingFactorialNotPi TimesRollTypeImaginarySquare Root
Dyadic AddSubtractTimesDivideResiduePowerLogarithmMinimumMaximumBinomialComparison functionsBoolean functions (And, Or, Nand, Nor) ∙ GCDLCMCircularComplexRoot
Non-Scalar
Structural ShapeReshapeTallyDepthRavelEnlistTableCatenateReverseRotateTransposeRazeMixSplitEncloseNestCut (K)PairLinkPartitioned EnclosePartition
Selection FirstPickTakeDropUniqueIdentityStopSelectReplicateExpandSet functions (IntersectionUnionWithout) ∙ Bracket indexingIndexCartesian ProductSort
Selector Index generatorGradeIndex OfInterval IndexIndicesDealPrefix and suffix vectors
Computational MatchNot MatchMembershipFindNub SieveEncodeDecodeMatrix InverseMatrix DivideFormatExecuteMaterialiseRange
Operators Monadic EachCommuteConstantReplicateExpandReduceWindowed ReduceScanOuter ProductKeyI-BeamSpawnFunction axis
Dyadic BindCompositions (Compose, Reverse Compose, Beside, Withe, Atop, Over) ∙ Inner ProductDeterminantPowerAtUnderRankDepthVariantStencilCutDirect definition (operator)
Quad names Index originComparison toleranceMigration levelAtomic vector