Data commit

Task/Entropy/Jsish/entropy.jsish

@@ -0,0 +1,30 @@
+/* Shannon entropy, in Jsish */
+
+function values(obj:object):array {
+    var vals = [];
+        for (var key in obj) vals.push(obj[key]);
+    return vals;
+}
+
+function entropy(s) {
+    var split = s.split('');
+    var counter = {};
+    split.forEach(function(ch) {
+        if (!counter[ch]) counter[ch] = 1;
+        else counter[ch]++;
+    });
+
+    var lengthf = s.length * 1.0;
+    var counts = values(counter);
+    return -1 * counts.map(function(count) {
+        return count / lengthf * (Math.log(count / lengthf) / Math.log(2));
+        })
+        .reduce(function(a, b) { return a + b; }
+    );
+};
+
+if (Interp.conf('unitTest')) {
+;    entropy('1223334444');
+;    entropy('Rosetta Code');
+;    entropy('password');
+}