Question

我正在尝试使用python，sqlalchemy和psycopg2驱动程序，从shapefile到geodataframe，再到安装了this question的postgis的postgres数据库。

我将几何转换为WKB十六进制字符串，并使用df.to_sql()成功导入了标准数据框。

运行alter table查询时出现错误：

sqlalchemy.exc.DataError: (psycopg2.errors.InvalidParameterValue) Geometry type (MultiPolygon) does not match column type (Polygon)

Answer 1

重写@Hugh_Kelley的功能以使其更快。

def _explode(indf):
    count_mp = 0
    outdf = gpd.GeoDataFrame(columns=indf.columns)
    outdf = indf[indf.geometry.type == 'Polygon']
    indf = indf[indf.geometry.type != 'Polygon']
    for idx, row in indf.iterrows():
        if type(row.geometry) == MultiPolygon:
            count_mp = count_mp + 1
            multdf = gpd.GeoDataFrame(columns=indf.columns)
            recs = len(row.geometry)
            multdf = multdf.append([row]*recs,ignore_index=True)
            for geom in range(recs):
                multdf.loc[geom,'geometry'] = row.geometry[geom]
            outdf = outdf.append(multdf,ignore_index=True)
        else:
            print(row)
    print("There were ", count_mp, "Multipolygons found and exploded")
    return outdf

Answer 2

这是因为shapefile将指示对于所得地理数据框的给定行可以是Polygon或Multipolygon的几何类型。

当转换为已知二进制十六进制字符串时，将包含此信息，并且在将文本转换为几何时会产生类型问题。

mhweber's gist中的爆炸功能可通过将多边形折成其componenet部分来解决此问题。

import geopandas as gpd
from shapely.geometry.polygon import Polygon
from shapely.geometry.multipolygon import MultiPolygon

def explode(indata):
    count_mp = 0
    indf = gpd.GeoDataFrame.from_file(indata)
    outdf = gpd.GeoDataFrame(columns=indf.columns)
    for idx, row in indf.iterrows():
        if type(row.geometry) == Polygon:
            outdf = outdf.append(row,ignore_index=True)
        if type(row.geometry) == MultiPolygon:
            count_mp = count_mp + 1
            multdf = gpd.GeoDataFrame(columns=indf.columns)
            recs = len(row.geometry)
            multdf = multdf.append([row]*recs,ignore_index=True)
            for geom in range(recs):
                multdf.loc[geom,'geometry'] = row.geometry[geom]
            outdf = outdf.append(multdf,ignore_index=True)
    print("There were ", count_mp, "Multipolygons found and exploded")
    return outdf

我添加了一个副作用，以打印发现的多多边形数量。

奇怪的是，您应该研究这些，以确保爆炸功能不会破坏所需的关系。

Answer 3

对于仍然回到这篇文章的人：The explode method 是（现在相当长的一段时间）GeoPandas api 的一部分：

gpd.GeoDataFrame.explode()

几何类型Multipolygon与列类型多边形不匹配

3 个答案: