Question

众所周知的功能

from shapely.geometry import *
from shapely.wkt import loads

def cut(line, distance):
# Cuts a line in two at a distance from its starting point
if distance <= 0.0 or distance >= line.length:
    return [LineString(line)]
coords = list(line.coords)
for i, p in enumerate(coords):
    pd = line.project(Point(p))
    if pd == distance:
        return [
            LineString(coords[:i+1]),
            LineString(coords[i:])]
    if pd > distance:
        cp = line.interpolate(distance)
        return [
            LineString(coords[:i] + [(cp.x, cp.y)]),
            LineString([(cp.x, cp.y)] + coords[i:])]

将形状上的线串分成两行距离。

我需要做的是从线上切割一段一定长度的线，在线的某个位置

示例行：

line = loads("LINESTRING (12.0133696 47.8217147, 12.0132944 47.8216655, 12.0132056 47.8215749, 12.0131542 47.8215034, 12.0130522 47.8212931, 12.0129941 47.8211294, 12.0130381 47.8209553, 12.0131116 47.8208718, 12.013184 47.8208107, 12.0133547 47.8207312, 12.0135537 47.8206727, 12.013915 47.8206019, 12.0141624 47.8205671, 12.0144317 47.8204965)")

我尝试了一种方法，通过应用上面的切割功能来获得一些线串之间的差异，但由于形状限制，结果并不好。

有什么想法吗？

Answer 1

我会自己回答，并对改进感到高兴：

def cut_piece(line,distance, lgth):
    """ From a linestring, this cuts a piece of length lgth at distance.
    Needs cut(line,distance) func from above ;-) 
    """
    precut = cut(line,distance)[1]
    result = cut(precut,lgth)[0]
    return result

Answer 2

您还可以使用交集并对插值进行归一化以获得特定范围内的曲线：

def cut(line, distance):
    if distance <= 0.0 :#line.length:
        return [None, LineString(line)]
    elif distance >= 1.0:
        return [LineString(line), None]
    coords = list(line.coords)
    for i, p in enumerate(coords):
        pd = line.project(Point(p), normalized=True)
        if pd == distance:
            return [
                LineString(coords[:i+1]),
                LineString(coords[i:])]
        if pd > distance:
            cp = line.interpolate(distance, normalized=True)
            return [
                LineString(coords[:i] + [(cp.x, cp.y)]),
                LineString([(cp.x, cp.y)] + coords[i:])]

def cut_piece(line,distance1, distance2):
    """ From a linestring, this cuts a piece of length lgth at distance.
    Needs cut(line,distance) func from above ;-) 
    """
    l1 = cut(line, distance1)[1]
    l2 = cut(line, distance2)[0]
    result = l1.intersection(l2)
    return result

示例：

cir = Point(0.0, 0.0).buffer(200).exterior
cir.coords = list(cir.coords)[::-1] # to flip the curve direction
print(cir.is_ccw)
d = cut_piece(cir,0.25, 0.75)

example

身材匀称：在两个切割点处用线绳切割一块

2 个答案: