Entropy: Difference between revisions

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@@ Line 1,962: / Line 1,962: @@
 (setq LN2 0.693147180559945309417)
-(de freq-table (Str)
+(de tabulate-chars (Str)
    (let Map NIL
       (for Ch (chop Str)
@@ Line 1,972: / Line 1,972: @@
 (de entropy (Str)
    (let (
-      Sz   (length Str)
+      Sz    (length Str)
-      S    0
+      Hist  (tabulate-chars Str)
    )
+   (*/
-   (for Counts (freq-table Str)
+      (sum
-      (let R (*/ (cdr Counts) 1. Sz)
-         (setq S (- S (*/ R (log R) 1.)))))
+         '((Pair)
-   (*/ S 1. LN2)))
+            (let R (*/ (cdr Pair) 1. Sz)
+               (- (*/ R (log R) 1.))))
+         Hist)
+. LN2)))
 </lang>
 {{Out}}
@@ Line 1,985: / Line 1,989: @@
 -> "1.84643934"
 </pre>
 =={{header|PL/I}}==
 <lang pli>*process source xref attributes or(!);