tasks a-s

Task/Run-length-encoding/Python/run-length-encoding-1.py

@@ -0,0 +1,29 @@
+def encode(input_string):
+    count = 1
+    prev = ''
+    lst = []
+    for character in input_string:
+        if character != prev:
+            if prev:
+                entry = (prev,count)
+                lst.append(entry)
+                #print lst
+            count = 1
+            prev = character
+        else:
+            count += 1
+    else:
+        entry = (character,count)
+        lst.append(entry)
+    return lst
+
+
+def decode(lst):
+    q = ""
+    for character, count in lst:
+        q += character * count
+    return q
+
+#Method call
+encode("aaaaahhhhhhmmmmmmmuiiiiiiiaaaaaa")
+decode([('a', 5), ('h', 6), ('m', 7), ('u', 1), ('i', 7), ('a', 6)])

Task/Run-length-encoding/Python/run-length-encoding-2.py

@@ -0,0 +1,9 @@
+from itertools import groupby
+def encode(input_string):
+    return [(len(list(g)), k) for k,g in groupby(input_string)]
+
+def decode(lst):
+    return ''.join(c * n for n,c in lst)
+
+encode("aaaaahhhhhhmmmmmmmuiiiiiiiaaaaaa")
+decode([(5, 'a'), (6, 'h'), (7, 'm'), (1, 'u'), (7, 'i'), (6, 'a')])

Task/Run-length-encoding/Python/run-length-encoding-3.py

@@ -0,0 +1,22 @@
+from re import sub
+
+def encode(text):
+    '''
+    Doctest:
+        >>> encode('WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW')
+        '12W1B12W3B24W1B14W'
+    '''
+    return sub(r'(.)\1*', lambda m: str(len(m.group(0))) + m.group(1),
+               text)
+
+def decode(text):
+    '''
+    Doctest:
+        >>> decode('12W1B12W3B24W1B14W')
+        'WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW'
+    '''
+    return sub(r'(\d+)(\D)', lambda m: m.group(2) * int(m.group(1)),
+               text)
+
+textin = "WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW"
+assert decode(encode(textin)) == textin