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(Created page with "{{Built-in|Union|∪}} is a dyadic set function which computes the set union of the two vector arguments. == Example...") |
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== Examples == | == Examples == | ||
Both arguments of Intersection is usually restricted to [[vector|vectors]]. Unlike sets in the mathematical sense, duplicate elements are allowed in both sides, and Union is usually implemented as "left argument unchanged, plus the elements of right argument not in the left argument" < | Both arguments of Intersection is usually restricted to [[vector|vectors]]. Unlike sets in the mathematical sense, duplicate elements are allowed in both sides, and Union is usually implemented as "left argument unchanged, plus the elements of right argument not in the left argument" <syntaxhighlight lang=apl inline>X,(~Y∊X)/Y</syntaxhighlight>. This preserves the order and multiplicity in both arguments, the left one taking precedence. Both arguments can be [[nested array|nested arrays]]. | ||
< | <syntaxhighlight lang=apl> | ||
'WASH' ∪ 'SHOUT' | 'WASH' ∪ 'SHOUT' | ||
WASHOUT | WASHOUT | ||
| Line 14: | Line 14: | ||
│THIS│THAT│THE│OTHER│THAN│AND│ | │THIS│THAT│THE│OTHER│THAN│AND│ | ||
└────┴────┴───┴─────┴────┴───┘ | └────┴────┴───┴─────┴────┴───┘ | ||
</ | </syntaxhighlight> | ||
== Extension == | |||
Some dialects allow Union to work on [[major cell]]s: | |||
[https://tio.run/##SyzI0U2pTMzJT9dNrShJzUtJTfn/P@JR2wQTBaNHvVvUHR2dnJyBQJ0rEihoDBN0cXF0VOd61DcVKBjxqGNV5P//AA Try it online!]<syntaxhighlight lang=apl> | |||
X←4 2⍴'AABBCCCC' | |||
Y←3 2⍴'AADDAA' | |||
X∩Y | |||
AA | |||
BB | |||
CC | |||
CC | |||
DD | |||
</syntaxhighlight>{{Works in|[[Extended Dyalog APL]]}} | |||
Others can easily define such a function: | |||
[https://tio.run/##SyzI0U2pTMzJT///P@JR2wQTBaNHvVvUHR2dnJyBQJ0rEihoDBN0cXF0VOcKzcvMzwMKVz/q3fWod9Wj3q2PevY/6l2h8ahzEVBI0wYsvhkoXsv1qG8qUGWEAliPQuT//wA Try it online!]<syntaxhighlight lang=apl> | |||
X←4 2⍴'AABBCCCC' | |||
Y←3 2⍴'AADDAA' | |||
Intersection←{⍺⌿⍨(≢⍵)≥⍵⍳⍺} | |||
X Intersection Y | |||
AA | |||
BB | |||
CC | |||
CC | |||
DD | |||
</syntaxhighlight>{{Works in|[[Dyalog APL]]}} | |||
== External Links == | == External Links == | ||
=== Documentation === | === Documentation === | ||
* [ | * [https://help.dyalog.com/latest/#Language/Primitive%20Functions/Union.htm Dyalog] | ||
* [http://microapl.com/apl_help/ch_020_020_393.htm APLX] | * [http://microapl.com/apl_help/ch_020_020_393.htm APLX] | ||
{{APL built-ins}}[[Category:Primitive functions]][[Category:Set functions]] | {{APL built-ins}}[[Category:Primitive functions]][[Category:Set functions]] | ||