September 2017 Update

Task/Entropy/Jq/entropy-1.jq

@@ -0,0 +1,10 @@
+# Input: an array of strings.
+# Output: an object with the strings as keys, the values of which are the corresponding frequencies.
+def counter:
+  reduce .[] as $item ( {}; .[$item] += 1 ) ;
+
+# entropy in bits of the input string
+def entropy:
+  (explode | map( [.] | implode ) | counter
+    | [ .[] | . * log ] | add) as $sum
+  | ((length|log) - ($sum / length)) / (2|log) ;

Task/Entropy/Jq/entropy-2.jq

@@ -0,0 +1 @@
+"1223334444" | entropy # => 1.8464393446710154