From 78c8874102e1d020f569363bd064c67c81bf1b2d Mon Sep 17 00:00:00 2001
From: Matthieu Bessat <mbess@mbess.net>
Date: Thu, 4 Jul 2024 23:06:36 +0200
Subject: [PATCH] refactor: wrap.py

---
 gift_wrapping/wrap.py | 62 +++++++++++--------------------------------
 1 file changed, 16 insertions(+), 46 deletions(-)

diff --git a/gift_wrapping/wrap.py b/gift_wrapping/wrap.py
index 74bd15a..23e9cc0 100644
--- a/gift_wrapping/wrap.py
+++ b/gift_wrapping/wrap.py
@@ -2,56 +2,29 @@
 # https://en.wikipedia.org/wiki/Gift_wrapping_algorithm
 # Date: 2021-11-16
 
-import matplotlib.pyplot as plt
-import math
 import random
+import matplotlib.pyplot as plt
+
 
 def generate_points(n=100):
     X = []
     Y = []
-    for i in range(n):
+    for _i in range(n):
         X.append(random.random())
         Y.append(random.random())
-    plt.plot(X, Y, '.')
-    return [(X[i],Y[i]) for i in range(n)]
+    plt.plot(X, Y, ".")
+    return [(X[i], Y[i]) for i in range(n)]
 
-# def angle(p1, p2, p3):
-#     p1, p2, p3 = p3, p2, p1
-#     print(p1, p2, p3)
-#     if p1 == p3: return math.pi
-#     x1, y1 = p2[0]-p1[0], p2[1]-p1[1]
-#     x2, y2 = p3[0]-p2[0], p3[1]-p2[1]
-#     d = x1*y2-y1*x2
-#     n1 = math.hypot(x1, y1)
-#     n2 = math.hypot(x2, y2)
-#     if d == 0 or n1*n2 == 0:
-#         l = x1/x2
-#         if l >= 0: return 0
-#         return math.pi
-#     dp = x1*x2 + y1*y2
-#     c = math.acos(dp/(n1*n2))
-#     b = (c if d > 0 else -c) % 2*math.pi
-#     return math.pi*2-b
 
 def cross_product(u, v):
     x1, y1 = u
     x2, y2 = v
-    n1 = math.hypot(x1, y1)
-    n2 = math.hypot(x2, y2)
-    return (x1*y2-x2*y1)
-
-# def angle(p1, p2, p3):
-#     x1, y1 = p2[0]-p1[0], p2[1]-p1[1]
-#     x2, y2 = p3[0]-p2[0], p3[1]-p2[1]
-#     a = (math.atan2(y1, x1) - math.atan2(y2, x2))
-#     if a < 0:
-#         a = math.pi
-#     return a
+    return x1 * y2 - x2 * y1
 
 
 def gift_wrapping(points):
     convex_hull = []
-    x_sorted = list(sorted(points, key=lambda point: point[0]))
+    x_sorted = sorted(points, key=lambda point: point[0])
     left_most = x_sorted[0]
     point_on_hull = left_most
     endpoint = None
@@ -59,31 +32,28 @@ def gift_wrapping(points):
         convex_hull.append(point_on_hull)
         endpoint = points[0]
         for point in points:
-            cp = cross_product((
-                endpoint[0] - point_on_hull[0],
-                endpoint[1] - point_on_hull[1]
-            ), (
-                point[0] - point_on_hull[0],
-                point[1] - point_on_hull[1]
-            ))
+            cp = cross_product(
+                (endpoint[0] - point_on_hull[0], endpoint[1] - point_on_hull[1]),
+                (point[0] - point_on_hull[0], point[1] - point_on_hull[1]),
+            )
             if endpoint == point_on_hull or cp < 0:
                 endpoint = point
         point_on_hull = endpoint
     return convex_hull
 
+
 def draw_points(points, with_edge=False):
     X, Y = [], []
     for p in points:
         X.append(p[0])
         Y.append(p[1])
-    plt.plot(X, Y, '.' if not with_edge else '')
+    plt.plot(X, Y, "." if not with_edge else "")
+
 
 pts = generate_points(50)
 
-#pts = [(0.1, 1), (0.2, 0.4), (0.2, 0.15), (0.4, 0.25), (0.6, 0.8), (0.55, 0.3), (0.7, 0.2), (0.5, 0.5), (0.4, 0.7), (0.3, 0.1)]
 print(pts)
-
 draw_points(pts)
-hull=gift_wrapping(pts)
-draw_points(hull+[hull[0]], True)
+hull = gift_wrapping(pts)
+draw_points(hull + [hull[0]], True)
 plt.show()