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June 2018 Update

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This commit is contained in:
Ingy döt Net 2018-06-22 20:57:24 +00:00
parent ba8067c3b7
commit 22f33d4004
5278 changed files with 84726 additions and 14379 deletions
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4
Task/Entropy/Common-Lisp/entropy.lisp → Task/Entropy/Common-Lisp/entropy-1.lisp
View file

@ -3,6 +3,8 @@
(entropy 0))
(mapc (lambda (c) (setf (gethash c table) (+ (gethash c table 0) 1)))
(coerce string 'list))
(maphash (lambda (k v) (decf entropy (* (/ v (length input-string)) (log (/ v (length input-string)) 2))))
(maphash (lambda (k v)
(decf entropy (* (/ v (length input-string))
(log (/ v (length input-string)) 2))))
table)
entropy))

8
Task/Entropy/Common-Lisp/entropy-2.lisp Normal file
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@ -0,0 +1,8 @@
(defun entropy (string &aux (length (length string)))
(declare (type string string))
(let ((table (make-hash-table)))
(loop for char across string
do (incf (gethash char table 0)))
(- (loop for freq being each hash-value in table
for freq/length = (/ freq length)
sum (* freq/length (log freq/length 2))))))