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{{Built-in|Deal|?}} is a [[dyadic]] [[primitive function]] which returns a random [[wikipedia:permutation#k-permutations of n|partial permutation]]. The name ''Deal'' comes from the analogy of [[wikipedia:card game#deal|dealing cards]] in a card game such as Poker. Both [[argument|arguments]] of <source lang=apl inline>k?n</source> must be non-negative integer [[scalar|scalars]] with <source lang=apl inline>k≤n</source>, and Deal generates a random k-permutation by selecting <source lang=apl inline>k</source> numbers from the first <source lang=apl inline>n</source> [[Index|indices]] without replacement | {{Built-in|Deal|?}} is a [[dyadic]] [[primitive function]] which returns a random [[wikipedia:permutation#k-permutations of n|partial permutation]]. The name ''Deal'' comes from the analogy of [[wikipedia:card game#deal|dealing cards]] in a card game such as Poker. Both [[argument|arguments]] of <source lang=apl inline>k?n</source> must be non-negative integer [[scalar|scalars]] with <source lang=apl inline>k≤n</source>, and Deal generates a random k-permutation by selecting <source lang=apl inline>k</source> numbers from the first <source lang=apl inline>n</source> [[Index|indices]] without replacement. Deal shares the [[glyph]] <source lang=apl inline>?</source> with the monadic scalar function [[Roll]]. | ||
== Examples == | == Examples == | ||
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└──┴──┴──┴──┴──┘ | └──┴──┴──┴──┴──┘ | ||
</source> | </source> | ||
[[J]] assigns [[function rank|rank]] 0 to Deal, so it can be used to generate multiple permutations at once. This behavior can be mimicked in other APLs by writing <source lang=apl inline>?⍤0</source>, which uses the [[Rank (operator)|rank operator]] <source lang=apl inline>⍤</source>. | |||
<source lang=j> | |||
?~ 5$10 NB. Generate five permutations of 0 to 9 at once | |||
9 8 3 0 6 1 2 5 4 7 | |||
7 2 4 1 0 5 6 9 8 3 | |||
3 0 7 2 9 1 5 8 4 6 | |||
2 1 5 0 3 6 4 7 8 9 | |||
3 7 5 9 0 2 6 8 4 1 | |||
</source>{{Works in|[[J]]}} | |||
== Description == | == Description == | ||