29 lines
1 KiB
Common Lisp
29 lines
1 KiB
Common Lisp
Remark- The native '''shuffle''' function implementation in EchoLisp has been replaced by this one.
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Thx Rosetta Code.
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(lib 'list) ;; for list-permute
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;; use "inside-out" algorithm, no swapping needed.
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;; returns a random permutation vector of [0 .. n-1]
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(define (rpv n (j))
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(define v (make-vector n))
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(for [(i n)]
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(set! j (random (1+ i)))
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(when (!= i j) (vector-set! v i [v j]))
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(vector-set! v j i))
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v)
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;; apply to any kind of list
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(define (k-shuffle list)
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(list-permute list (vector->list (rpv (length list)))))
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;; out
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(k-shuffle (iota 17))
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→ (16 7 11 10 0 9 15 12 13 8 4 2 14 3 6 5 1)
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(k-shuffle
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'(adrien 🎸 alexandre 🚂 antoine 🍼 ben 📚 georges 📷 julie 🎥 marine 🐼 nathalie 🍕 ))
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→ (marine alexandre 🎥 julie 🎸 ben 🍼 nathalie 📚 georges 🚂 antoine adrien 🐼 📷 🍕)
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(shuffle ;; native
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'(adrien 🎸 alexandre 🚂 antoine 🍼 ben 📚 georges 📷 julie 🎥 marine 🐼 nathalie 🍕 ))
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→ (antoine 🎥 🚂 marine adrien nathalie 🍼 🍕 ben 🐼 julie 📷 📚 🎸 alexandre georges)
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