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{{Built-in|Without|~}}, '''Set Difference''', '''Excluding''', or '''Less''', is a [[dyadic]] [[set function]] which computes the [[wikipedia:set difference|set difference]] of the two [[vector]] [[argument|arguments]]. It shares the [[glyph]] <source lang=apl inline>~</ | {{Built-in|Without|~}}, '''Set Difference''', '''Excluding''', or '''Less''', is a [[dyadic]] [[set function]] which computes the [[wikipedia:set difference|set difference]] of the two [[vector]] [[argument|arguments]]. It shares the [[glyph]] <source lang=apl inline>~</syntaxhighlight> with the monadic function [[Not]]. | ||
== Examples == | == Examples == | ||
Both arguments of Without is usually restricted to [[vector|vectors]]. Unlike sets in the mathematical sense, duplicate elements are allowed in both sides, and Without is usually implemented as "left argument filtered by the absence in the right argument" <source lang=apl inline>(~X∊Y)/X</ | Both arguments of Without is usually restricted to [[vector|vectors]]. Unlike sets in the mathematical sense, duplicate elements are allowed in both sides, and Without is usually implemented as "left argument filtered by the absence in the right argument" <source lang=apl inline>(~X∊Y)/X</syntaxhighlight>. This preserves the order and multiplicity in the left argument. Both arguments can be [[nested array|nested arrays]]. | ||
<source lang=apl> | <source lang=apl> | ||
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│THIS│THAT│ | │THIS│THAT│ | ||
└────┴────┘ | └────┴────┘ | ||
</ | </syntaxhighlight> | ||
== Extension == | == Extension == | ||
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CC | CC | ||
CC | CC | ||
</ | </syntaxhighlight>{{Works in|[[Extended Dyalog APL]]}} | ||
Others can easily define such a function: | Others can easily define such a function: | ||
[https://tio.run/##SyzI0U2pTMzJT///P@JR2wQTBaNHvVvUHR2dnJyBQJ0rEihojBB0dFTnCs8sycgvLQFKVD/q3fWoZ/@j3hV1Go96Nz/qXAQU0HzU0QUSB/J7t9ZyPeqbClQZoQDVpRD5/z8A Try it online!]<source lang=apl> | [https://tio.run/##SyzI0U2pTMzJT///P@JR2wQTBaNHvVvUHR2dnJyBQJ0rEihojBB0dFTnCs8sycgvLQFKVD/q3fWoZ/@j3hV1Go96Nz/qXAQU0HzU0QUSB/J7t9ZyPeqbClQZoQDVpRD5/z8A Try it online!]<source lang=apl> | ||
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CC | CC | ||
CC | CC | ||
</ | </syntaxhighlight>{{Works in|[[Dyalog APL]]}} | ||
== External Links == | == External Links == | ||