geopandas.read_postgis#

geopandas.read_postgis(sql, con, geom_col='geom', crs=None, index_col=None, coerce_float=True, parse_dates=None, params=None, chunksize=None)[source]#

Returns a GeoDataFrame corresponding to the result of the query string, which must contain a geometry column in WKB representation.

It is also possible to use read_file() to read from a database. Especially for file geodatabases like GeoPackage or SpatiaLite this can be easier.

Parameters:
sqlstring

SQL query to execute in selecting entries from database, or name of the table to read from the database.

consqlalchemy.engine.Connection or sqlalchemy.engine.Engine

Active connection to the database to query.

geom_colstring, default ‘geom’

column name to convert to shapely geometries

crsdict or str, optional

CRS to use for the returned GeoDataFrame; if not set, tries to determine CRS from the SRID associated with the first geometry in the database, and assigns that to all geometries.

chunksizeint, default None

If specified, return an iterator where chunksize is the number of rows to include in each chunk.

See the documentation for pandas.read_sql for further explanation
of the following parameters:
index_col, coerce_float, parse_dates, params, chunksize
Returns:
GeoDataFrame

Examples

PostGIS

>>> from sqlalchemy import create_engine  
>>> db_connection_url = "postgresql://myusername:mypassword@myhost:5432/mydatabase"
>>> con = create_engine(db_connection_url)  
>>> sql = "SELECT geom, highway FROM roads"
>>> df = geopandas.read_postgis(sql, con)  

SpatiaLite

>>> sql = "SELECT ST_AsBinary(geom) AS geom, highway FROM roads"
>>> df = geopandas.read_postgis(sql, con)