string compression solution

Author: nickolasteixeira

Python/chapter01/1.6 - String Compression/Nick.py

@@ -0,0 +1,49 @@
+#!/usr/bin/python3
+import unittest
+
+
+def string_compression(string):
+    '''Implement a method to perform basic string compression using the counts
+of repeated characters. For example, the string aabcccccaaa would become a2blc5a3. If the
+"compressed" string would not become smaller than the original string, your method should return
+the original string. You can assume the string has only uppercase and lowercase letters (a - z). '''
+    if not isinstance(string, str):
+        return False
+
+    new_str = ''
+    count, new_count = 0, 0
+    for idx in range(len(string) - 1):
+        count += 1
+        if string[idx] is not string[idx + 1]:
+            new_str += string[idx]
+            new_str += str(count)
+            count = 0
+        if idx is len(string) - 2:
+            if string[idx] is string[idx + 1]:
+                new_str += string[idx]
+                new_str += str(count + 1)
+            else:
+                new_str += string[idx + 1]
+                new_str += '1'
+
+    for letter in new_str:
+        if letter is '1':
+            new_count += 1
+
+    if len(string) // new_count is 1:
+        return string
+    return new_str
+
+
+class Test(unittest.TestCase):
+    def test1(self):
+        self.assertEqual(string_compression('aabcccccaaa'), 'a2b1c5a3')
+        self.assertEqual(
+            string_compression('bbaaaabcdeeefff'),
+            'b2a4b1c1d1e3f3')
+        self.assertEqual(string_compression('abcdef'), 'abcdef')
+        self.assertNotEqual(string_compression('abcdef'), 'a1b1c1d1e1f1')
+
+
+if __name__ == '__main__':
+    unittest.main()