1 files changed, 48 insertions, 0 deletions
diff --git a/prob/random_walk_demo.py b/prob/random_walk_demo.py
new file mode 100644
index 0000000..6212528
--- /dev/null
+++ b/prob/random_walk_demo.py
@@ -0,0 +1,48 @@
+
+import random
+
+
+def random_walk(N):
+    x, y = 0, 0
+    choices = ['N', 'S', 'E', 'W']
+    for i in range(N):
+        step = random.choice(choices)
+        if step == 'N':
+            y += 1
+        elif step == 'S':
+            y -= 1
+        elif step == 'E':
+            x += 1
+        else:
+            x -= 1
+    return x, y
+
+
+def random_walk_2(N):
+    x, y = 0, 0
+    for i in range(N):
+        dx, dy = random.choice([[0, 1], [0, -1], [1, 0], [-1, 0]])
+        x += dx
+        y += dy
+    return x, y
+
+
+def distance_from_home(x, y):
+    return abs(x) + abs(y)
+
+
+if __name__ == '__main__':
+    # for i in range(25):
+    #     x, y = random_walk_2(10)
+    #     print(f'x = {x}, y = {y}, distance from home: {distance_from_home(x, y)}')
+
+    number_of_walks = 50000
+    for walk_length in range(1, 31):
+        no_transport = 0
+        for i in range(number_of_walks):
+            x, y = random_walk(walk_length)
+            dist = distance_from_home(x, y)
+            if dist <= 5:
+                no_transport += 1
+        no_transport_percentage = float(no_transport)/number_of_walks
+        print(f'walk_length: {walk_length}, no_transport_percentage: {no_transport_percentage}')