Add count_group

Author: rjLelis

README.md

@@ -31,6 +31,10 @@ The [object serializer](/object-serializer) takes an object as a argument and se
 
 [socket](/socket) has a [`client`][client] and a [`server`][server]. The [`client`][client] sends to the [`server`][server] a "`Hello, World`", which in return sends back to the [`client`][client] the same message.
 
+## Count group
+
+The [count group](./count_group/count_group.py) counts how many times the letters repeats consecutively.
+
 ## Learning source
 
 * [A byte of python(PDF)](https://edisciplinas.usp.br/pluginfile.php/3252353/mod_resource/content/1/b_Swaroop_Byte_of_python.pdf)

count_group/README.md

@@ -0,0 +1,10 @@
+# Count group
+
+Takes a string and returns a `list` of tuples where the first element is the letter and second is how many of the letters repeats consecutively
+
+### Worked concepts
+* For loops
+* enumerate
+* for-else
+* Type hints
+* assert statement

count_group/count_group.py

@@ -0,0 +1,21 @@
+
+def count_group(string: str) -> list:
+    counter = 0
+    group = []
+    temp = string[0]
+    for index, s in enumerate(string):
+        if temp == s:
+            counter += 1
+        else:
+            group.append((temp, counter))
+            counter = 1
+        temp = s
+    else:
+        group.append((temp, counter))
+
+    return group
+
+def test_short_string():
+    assert count_group('') == []
+    assert count_group('a') == [('a', 1)]
+    assert count_group('aaaabbbcca') == [('a', 4), ('b', 3), ('c', 2), ('a', 1)]