如何将 LineString 拆分为段

Question

我的数据集由一个LineString组成，我想过滤掉这个LineString的各个线段。更准确地说，每个街道段。

到目前为止，我已经从数据集中提取了各个点并将它们保存在单独的列表中。此外，我想再次收集这些点并从中创建单独的 LineStrings 以将它们存储到 Geodataframe 中。数据具有以下形式：

LINESTRING (3275.284016199762 340555.8579582386, 3241.504528076811 340504.1348617533, 3245.415803206172 340501.457084205, 3280.414559049542 340552.7138220053, 3285.19053022

我的问题是我必须为每次迭代创建并显式保存一个单独的 LineString。谁能帮我这个？有更好的方法吗？

from shapely.geometry import Point, LineString

#Loop over LineString and gather Points
c=[]

for i in range(0,end):
    c.append(Point(route1.coords[i]))


iterator=len(c)
max=len(c)-1

#Loop to store LineStrings - got stuck here
for i in np.arange(0,iterator):
    if i<max:
        LineString([c[i], c[i+1]]).wkt

    else:
        break;

输出应如下所示：

Linestring(Point A, Point B)  
Linestring(Point B, Point C)  
Linestring(Point C, Point D)  
...  
Linestring(Point Y, Point Z)

Answer 1

欢迎来到 SO。

您不必编写代码来拆分 LineString。让 PostGIS 来完成这项工作 :) 下面的快速示例使用 CTE to ST_DumpPoints from your LineString, and subsequently creates another line with path,path+1 using the window function lead():

WITH j AS (
  SELECT ST_DumpPoints('LINESTRING (10 10, 12 12, 14 14, 16 16, 18 18)') AS g
)
SELECT ST_AsText(point) FROM (
  SELECT ST_MakeLine((g).geom, lead((g).geom,1) OVER ()) AS point
  FROM j) i
WHERE i.point IS NOT NULL

            st_astext        
-------------------------
 LINESTRING(10 10,12 12)
 LINESTRING(12 12,14 14)
 LINESTRING(14 14,16 16)
 LINESTRING(16 16,18 18)
(4 Zeilen)

Answer 2

说到 Shapely，它没有提供将曲线对象（LineString 或 LinearRing）分割成段的功能，因此您必须自己编写。这是一个如何使用 zip to iterate over pairs of coordinates and map 到 LineString 的例子：

from shapely.geometry import LineString, LinearRing


def segments(curve):
    return list(map(LineString, zip(curve.coords[:-1], curve.coords[1:])))


line = LineString([(0, 0), (1, 1), (2, 2)])
ring = LinearRing([(0, 0), (1, 0), (1, 1), (0, 1)])

line_segments = segments(line)
for segment in line_segments:
    print(segment)
# LINESTRING (0 0, 1 1)
# LINESTRING (1 1, 2 2)

ring_segments = segments(ring)
for segment in ring_segments:
    print(segment)
# LINESTRING (0 0, 1 0)
# LINESTRING (1 0, 1 1)
# LINESTRING (1 1, 0 1)
# LINESTRING (0 1, 0 0)

如何将 LineString 拆分为段

How to split a LineString to segments

python

postgis

shapely

geopandas