25 lines
418 B
APL
25 lines
418 B
APL
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ENTROPY←{-+/R×2⍟R←(+⌿⍵∘.=∪⍵)÷⍴⍵}
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⍝ How it works:
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⎕←UNIQUE←∪X←'1223334444'
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1234
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⎕←TABLE_OF_OCCURENCES←X∘.=UNIQUE
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1 0 0 0
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0 1 0 0
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0 1 0 0
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0 0 1 0
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0 0 1 0
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0 0 1 0
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0 0 0 1
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0 0 0 1
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0 0 0 1
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0 0 0 1
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⎕←COUNT←+⌿TABLE_OF_OCCURENCES
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1 2 3 4
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⎕←N←⍴X
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10
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⎕←RATIO←COUNT÷N
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0.1 0.2 0.3 0.4
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-+/RATIO×2⍟RATIO
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1.846439345
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