有没有办法在python中使用shapely和geopandas找到3条或更多线相互接触的点坐标列表？

Question

我有一个 Geopandas DataFrame，每一行都包含一个匀称的 LineString。我需要找到三个或更多 LineStrings 相互接触的点列表。比如图Input image中，我需要三色线相交点的坐标。

找到三条线相交的所有点后，我需要将三条线合并形成两条线：1）粉色+紫色2）绿色+紫色。重叠应该没问题。

任何帮助将不胜感激。谢谢！

Answer 1

• 已使用几个国家/地区作为 LINESTRINGS 的来源
• 使用此数据集，只有两个点与三个选定的国家相交（根据可视化）
• 关键概念是内部连接点到点，然后找到重复次数超过要求的点

import geopandas as gpd
import shapely.geometry
import pandas as pd
import plotly.express as px

# some polygons
# fmt: off
gdf = gpd.read_file(gpd.datasets.get_path("naturalearth_lowres")).loc[lambda d: d["iso_a3"].isin(["BEL", "LUX", "NLD", "DEU", "AUT","POL"]), ["geometry", "iso_a3"]].reset_index(drop=True)
# fmt: on

# change to linestrings as per question
gdf["geometry"] = gdf["geometry"].apply(
    lambda p: shapely.geometry.LineString(p.exterior.coords)
)

# generate series of points from linestrings
points = (
    gdf["geometry"].apply(lambda l: l.coords).rename("point").explode().reset_index()
)

# 1. join all points to all points
# 2. exclude point to self
points = (
    points.merge(points, on=["point"])
    .drop_duplicates()
    .loc[lambda d: d["index_x"] != d["index_y"]]
)
# now find points that appera N times
n_times = (
    points.groupby(["point"])
    .size()
    .loc[lambda s: s >= 3]
    .reset_index()["point"]
    .apply(pd.Series)
)

# visualize to test...
px.scatter_mapbox(n_times, lon=0, lat=1, mapbox_style="carto-positron",).update_traces(
    marker_size=20
).update_layout(mapbox={"layers": [{"source": gdf.__geo_interface__, "type": "line"}]})