对多边形中的点进行计数，并将结果写入（Geo）数据帧

Question

我想计算每个多边形有多少个点

# Credits of this code go to: https://stackoverflow.com/questions/69642668/the-indices-of-the-two-geoseries-are-different-understanding-indices/69644010#69644010
import pandas as pd
import numpy as np
import geopandas as gpd
import shapely.geometry
import requests

# source some points and polygons
# fmt: off
dfp = pd.read_html("https://www.latlong.net/category/cities-235-15.html")[0]
dfp = gpd.GeoDataFrame(dfp, geometry=dfp.loc[:,["Longitude", "Latitude",]].apply(shapely.geometry.Point, axis=1))
res = requests.get("https://opendata.arcgis.com/datasets/69dc11c7386943b4ad8893c45648b1e1_0.geojson")
df_poly = gpd.GeoDataFrame.from_features(res.json())
# fmt: on

现在我{}这两个。我首先使用df_poly，以便将点dfp添加到GeoDataframe{}

df_poly.sjoin(dfp)

现在我想计算每个polygon有多少points。 我想

df_poly.sjoin(dfp).groupby('OBJECTID').count()

但这并没有在{}{}中添加一个{}，每个{}的{}

Answer 1

您需要使用merge将count()输出中的一列添加回原始数据帧。我使用了geometry列并将其重命名为n_points：

df_poly.merge(
    df_poly.sjoin(
        dfp
    ).groupby(
        'OBJECTID'
    ).count().geometry.rename(
        'n_points'
    ).reset_index())