Run-length added

mgechev · mgechev · commit 8a8f65385e7d · 2013-05-13T18:19:22.000+03:00
diff --git a/src/compression/runlength/runlength.js b/src/compression/runlength/runlength.js
@@ -0,0 +1,59 @@
+var str = 'Sample';
+
+/**
+ * Run-length encoding.
+ * The idea of this algorithm is to remove the usless zeros and
+ * give us representation of string in binary which in which the
+ * zeros will be stripped and replaced with their count.
+ */
+var runLengthEncoding = (function () { 
+
+    'use strict';
+
+    function convertToAscii(str) {
+        var result = '',
+            currentChar = '',
+            i = 0;
+        for (; i < str.length; i += 1) {
+            currentChar = str[i].charCodeAt(0).toString(2);
+            if (currentChar.length < 8) {
+                while (8 - currentChar.length) {
+                    currentChar = '0' + currentChar;
+                }
+            }
+            result += currentChar;
+        }
+        return result;
+    }
+     
+    function runLength(vector) {
+        var result = '',
+            zeros = 0,
+            zerosTemp = '',
+            wordLength = 0,
+            i = 0;
+        for (; i < vector.length; i += 1) {
+            if (vector[i] === '0') {
+                zeros += 1;
+            } else {
+                zerosTemp = zeros.toString(2);
+                wordLength = zerosTemp.length - 1;
+                while (wordLength) {
+                    result = result + '1';
+                    wordLength -= 1;
+                }
+                result += '0' + zerosTemp;
+                zeros = 0;
+            }
+        }
+        return result;
+    }
+     
+    return function (str) {
+        var asciiString = convertToAscii(str);
+        return runLength(asciiString);
+    }
+
+}());
+
+console.log(runLengthEncoding(str));
