动态和/或静态直线/正交/ X-Y凸壳

时间:2013-01-19 00:18:02

标签: python performance algorithm convex

我正在寻找一种处理2D动态rectilinear convex hulls的高效算法。

我编写了一个静态算法,但是虽然它在大多数情况下都有效,但它根本不起作用,所以我也在寻找静态直线凸包的资源。维基百科有一些关于算法的研究论文,但我无法访问它们。所以寻找其他资源或帮助编写代码。

任何帮助都会受到赞赏,这是Python中的一种算法,非常感谢。

当前静态代码:

def stepped_hull(points, is_sorted=False, return_sections=False):
    # May be equivalent to the orthogonal convex hull

    if not is_sorted:
        points = sorted(set(points))

    if len(points) <= 1:
        return points

    # Get extreme y points
    min_y = min(points, lambda p:p[1])
    max_y = max(points, lambda p:p[1])

    points_reversed = list(reversed(points))

    # Create upper section
    upper_left = build_stepped_upper(points, max_y)
    upper_right = build_stepped_upper(points_reversed, max_y)

    # Create lower section
    lower_left = build_stepped_lower(points, min_y)
    lower_right = build_stepped_lower(points_reversed, min_y)

    # Correct the ordering
    lower_right.reverse()
    upper_left.reverse()

    if return_sections:
        return lower_left, lower_right, upper_right, upper_left

    # Remove duplicate points
    hull = OrderedSet(lower_left + lower_right + upper_right + upper_left)
    return list(hull)

def build_stepped_upper(points, max_y):
    # Steps towards the highest y point

    section = [points[0]]

    if max_y != points[0]:
        for point in points:
            if point[1] >= section[-1][1]:
                section.append(point)

            if max_y == point:
                break
    return section

def build_stepped_lower(points, min_y):
    # Steps towards the lowest y point

    section = [points[0]]

    if min_y != points[0]:
        for point in points:
            if point[1] <= section[-1][1]:
                section.append(point)

            if min_y == point:
                break
    return section

0 个答案:

没有答案