Difference between revisions of "Commute"

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{{Built-in|Commute|⍨}} is a [[Primitive function|primitive]] [[monadic]] [[operator]] that takes a [[function]] on its left and returns a new function with swapped arguments.
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{{Built-in|Commute|⍨}} is a [[monadic operator]] that takes a [[[dyadic function]] as operand and modifies how the argument(s) of its derived functions are used. If the derived function is used monadically, the argument is also used as left argument. This usage is also known as '''Self''' or, more informally, '''Selfie'''. If the derived function is used dyadically, the arguments are swapped. This usage is also known as '''Swap'''.
  
 
== Examples ==
 
== Examples ==
  
Subtract one from every item of the input array.
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This decrements from the vector:
 
<source lang=apl>
 
<source lang=apl>
1 -⍨ 1 2 3
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      1 -⍨ 1 2 3
 +
0 1 2
 
</source>
 
</source>
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{{Works in|[[Dyalog APL]], [[dzaima/APL]], [[NARS2000]]}}
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Double:
 +
<source lang=apl>
 +
      +⍨1 2 3
 +
2 4 6
 +
</source>
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{{Works in|[[Dyalog APL]], [[dzaima/APL]], [[NARS2000]]}}
  
 
== External links ==
 
== External links ==
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=== Lessons ===
 
=== Lessons ===
  
* [https://chat.stackexchange.com/transcript/52405?m=40900200#40900200 APL Cultivation]
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* [https://chat.stackexchange.com/rooms/52405/conversation/lesson-3-some-apl-operators-----#40900200]
  
 
=== Documentation ===
 
=== Documentation ===

Revision as of 15:04, 26 April 2020

Commute () is a monadic operator that takes a [[[dyadic function]] as operand and modifies how the argument(s) of its derived functions are used. If the derived function is used monadically, the argument is also used as left argument. This usage is also known as Self or, more informally, Selfie. If the derived function is used dyadically, the arguments are swapped. This usage is also known as Swap.

Examples

This decrements from the vector:

      1 - 1 2 3
0 1 2

Double:

      +1 2 3
2 4 6

External links

Lessons

Documentation


APL built-ins [edit]
Primitive functions
Scalar
Monadic ConjugateNegateSignumReciprocalMagnitudeExponentialNatural LogarithmFloorCeilingFactorialNotPi TimesRollTypeImaginarySquare Root
Dyadic AddSubtractTimesDivideResiduePowerLogarithmMinimumMaximumBinomialComparison functionsBoolean functions (And, Or, Nand, Nor) ∙ GCDLCMCircularComplexRoot
Non-Scalar
Structural ShapeReshapeTallyDepthRavelEnlistTableCatenateReverseRotateTransposeRazeMixSplitEncloseNestCut (K)PairLinkPartitioned EnclosePartition
Selection FirstPickTakeDropUniqueIdentitySelectReplicateExpandSet functions (IntersectionUnionWithout) ∙ Bracket indexingIndex
Selector Index generatorGradeIndex OfInterval IndexIndicesDeal
Computational MatchNot MatchMembershipFindNub SieveEncodeDecodeMatrix InverseMatrix DivideFormatExecuteMaterialiseRange
Primitive operators Monadic EachCommuteConstantReplicateExpandReduceWindowed ReduceScanOuter ProductKeyI-beamSpawnFunction axis
Dyadic BindCompositions (Compose, Reverse Compose, Beside, Atop, Over) ∙ Inner ProductPowerAtUnderRankDepthVariantStencilCut (J)
Quad names
Arrays Index originMigration levelAtomic vector
Functions Case convertUnicode convert
Operators SearchReplace