我想在 QGIS 中用特定值分割一条线。我也可以根据拆分的长度拆分值吗？

Question

我有一些穿过多个多边形的多线字符串。当我拆分线时，我希望 QGIS 也相应地拆分分配给该线的值。例如。如果一条 100 米的线在分成 50/30/20 的段时具有值 20，我希望该值在相应的段中也拆分为 10/6/4。这可能吗，还是我在追求星星？

Answer 1

你已经标记了 geopandas 所以在 geopandas
首先创建一个 GeoDataFrame 多边形和以不同方式相交的线串
现在是迭代行字符串的情况
1. 为每条线找到它相交的多边形 https://geopandas.org/en/stable/docs/reference/api/geopandas.GeoSeries.intersection.html
2. 交点是一条线或multi-line通过比较线的长度来计算贡献
有可视化演示

import geopandas as gpd
import shapely

world = gpd.read_file(gpd.datasets.get_path("naturalearth_lowres"))

# some polygons
poly = world.loc[world["iso_a3"].isin(["UKR", "POL", "HUN"])].drop(columns=["pop_est","gdp_md_est"]).copy()

# some linestrings
line = gpd.GeoDataFrame(
    data={"val": [100, 200]},
    geometry=[
        shapely.geometry.LineString([poly.total_bounds[0:2], poly.total_bounds[2:4]]),
        shapely.geometry.LineString([poly.total_bounds[0:2]+.5, poly.total_bounds[2:4], poly.total_bounds[[0,3]]-1]),

    ],
    crs=poly.crs,
)

# initialise contibution from line,  zero
poly = poly.assign(**{f"val{l}":0 for l in range(len(line))})
# iterate over the lines
for n, (i, r) in enumerate(line.iterrows()):
    # iterate over intersections between line and polygons
    for ii, ls in poly.intersection(r["geometry"]).iteritems():
        if ls.is_empty or isinstance(ls,shapely.geometry.Point):
            continue
        geom = [ls] if isinstance(ls, shapely.geometry.LineString) else ls.geoms
        # work out contribution of each intersection segment
        for ls in geom:
            poly.loc[ii, f"val{n}"] +=  (ls.length / r["geometry"].length) * r["val"]


# visualise ...            
m = poly.explore(height=300, width=500)
line.explore(m=m)

我想在 QGIS 中用特定值分割一条线。我也可以根据拆分的长度拆分值吗？

I want to split a line with a specific value in QGIS. Can I also split the value accordingly to the length splitted?

geopandas

qgis