gift_wrapping/wrap.py

@@ -1,59 +0,0 @@
-# Gift wrapping algorithm
-# https://en.wikipedia.org/wiki/Gift_wrapping_algorithm
-# Date: 2021-11-16
-
-import random
-import matplotlib.pyplot as plt
-
-
-def generate_points(n=100):
-    X = []
-    Y = []
-    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)]
-
-
-def cross_product(u, v):
-    x1, y1 = u
-    x2, y2 = v
-    return x1 * y2 - x2 * y1
-
-
-def gift_wrapping(points):
-    convex_hull = []
-    x_sorted = sorted(points, key=lambda point: point[0])
-    left_most = x_sorted[0]
-    point_on_hull = left_most
-    endpoint = None
-    while endpoint != left_most:
-        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]),
-            )
-            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 "")
-
-
-pts = generate_points(50)
-
-print(pts)
-draw_points(pts)
-hull = gift_wrapping(pts)
-draw_points(hull + [hull[0]], True)
-plt.show()