Merge pull request keon#38 from probablytom/master

Added a Markov Chain implementation

README.md

@@ -73,6 +73,7 @@ Minimal and clean example implementations of data structures and algorithms in P
     - [find_path](graph/find_path.py)
     - [graph](graph/graph.py)
     - [traversal](graph/traversal.py)
+    - [markov_chain](graph/markov_chain.py)
 - [heap](heap)
     - [merge_sorted_k_lists](heap/merge_sorted_k_lists.py)
     - [skyline](heap/skyline.py)

graph/markov_chain.py

@@ -0,0 +1,26 @@
+import random
+
+my_chain = {
+    'A': {'A': 0.6,
+          'E': 0.4},
+    'E': {'A': 0.7,
+          'E': 0.3}
+}
+
+def __choose_state(state_map):
+    choice = random.random()
+    probability_reached = 0
+    for state, probability in state_map.items():
+        probability_reached += probability
+        if probability_reached > choice:
+            return state
+
+def next_state(chain, current_state):
+    next_state_map = chain.get(current_state)
+    next_state = __choose_state(next_state_map)
+    return next_state
+
+def iterating_markov_chain(chain, state):
+    while True:
+        state = next_state(chain, state)
+        yield state