Question

更新了Martin的解决方案（非常感谢）。想知道如何通过组合在LineString类中使用move方法。请查看为完成代码而需要传递的断言。任何进一步的指导将非常感谢。

class Point(object):
    def __init__(self, x, y):
        self.x = x
        self.y = y

    def move(self, dx, dy):
        self.x += dx
        self.y += dy


class LineString(object):
    def __init__(self, *points):
        self.points = [Point(*point) for point in points]

    def length(self):
        pairs = zip(self.points, self.points[1:])
        return sum(starmap(distance, pairs))

def distance(p1, p2):
    return math.sqrt((p1.x - p2.x)**2 + (p1.y - p2.y)**2)

if __name__ == '__main__':
    # Tests for LineString
    # ===================================
    lin1 = LineString((1, 1), (0, 2))

    assert lin1.length() == sqrt(2.0)

    lin1.move(-1, -1)  # Help with Composition needed 

    assert lin1[0].y == 0  # Inspect the y value of the start point.

    lin2 = LineString((1, 1), (1, 2), (2, 2))

    lin2.move(-1, -1)  # Move by -1 and -1 for x and y respectively

    assert lin2.length() == 2.0

    assert lin2[-1].x == 1  # Inspect the x value of the end point.

Answer 1

您发布的代码的更简洁和有效版本

from itertools import starmap

class Point:
    def __init__(self, x, y):
        self.x = x
        self.y = y

    def move(self, dx, dy):
        self.x += dx
        self.y += dy

class LineString:
    def __init__(self, *points):
        self.points = [Point(*point) for point in points]

    def length(self):
        pairs = zip(self.points, self.points[1:])
        return sum(starmap(distance, pairs))

def distance(p1, p2):
    return math.sqrt((p1.x - p2.x)**2 + (p1.y - p2.y)**2)

测试

import numpy as np

points = np.arange(20).reshape((-1, 2))
ls = LineString(*points)
ls.length()

返回25.455 = sqrt（8）* 9，这是正确的。

实现一个类来表示一个线串？

1 个答案: