test_euclid.py 文件源码

def test_segment_sort_along(p1, p2, tvals):
    # Get rid of pathological cases.
    assume(p1.distance(p2) > 0.001)

    tvals = [t / 100 for t in tvals]
    fuzz = [1e-10, -1e-10]
    points = [along_the_way(p1, p2, t) for t in tvals]
    points = [Point(x+f, y+f) for (x, y), f in zip(points, itertools.cycle(fuzz))]

    # Calculate the smallest distance between any pair of points.  If we get
    # the wrong answer from sort_along, then the total distance will be off by
    # at least twice this.
    min_gap = min(q1.distance(q2) for q1, q2 in all_pairs(points + [p1, p2]))

    seg = Segment(p1, p2)
    spoints = seg.sort_along(points)

    assert len(spoints) == len(points)
    assert all(pt in points for pt in spoints)

    original = Point(*p1).distance(Point(*p2))
    total = (
        Point(*p1).distance(Point(*spoints[0])) +
        sum(Point(*p).distance(Point(*q)) for p, q in adjacent_pairs(spoints)) +
        Point(*spoints[-1]).distance(Point(*p2))
    )
    # The total distance will be wrong by at least 2*min_gap if it is wrong.
    assert total - original < 2 * min_gap


# Bounds