How do I query the GeoDataFrame?

Question

I have a question on Geopandas.

I have a shape file for a country which I am loading into geopandas. The shape file has shape for all states in country.

I need to extract a single state. I have tried exploring documentation and stackoverflow but was unable to warp my mind around how to use query() method to retrieve the single state.

import geopandas as gpd
import os

# get current directory path
cur_dir = os.path.dirname(os.path.realpath(__file__))

gdf_shp_state = gpd.read_file(cur_dir + '/data/StateBoundary/StateBoundary.shp')
print(type(gdf_shp_state))
print(gdf_shp_state)

Output:

<class 'geopandas.geodataframe.GeoDataFrame'>
                   state                                           geometry
0      ANDAMAN & NICOBAR  (POLYGON ((10341718.474 1449533.160500001, 103...
1             CHANDIGARH  POLYGON ((8546255.616099998 3606050.813100003,...
2   DADAR & NAGAR HAVELI  (POLYGON ((8137193.4859 2315664.964499999, 813...
3            DAMAN & DIU  (POLYGON ((8111624.4714 2328002.898499999, 811...
4                  DELHI  POLYGON ((8583390.569699999 3359116.190099999,...
5                HARYANA  POLYGON ((8524318.5392 3516490.864500001, 8524...
6              JHARKHAND  POLYGON ((9762288.284699999 2772949.712499999,...

Question is : How do I query the GeoDataFrame?

There is a method called gdf_shp_state.query() and its expecting me to put a query as a string . Can someone help me provide an example query string which I need to use to get GeoDataFrame for single state?

Answer 1

geodataframes work the same way as regular dataframes, so the query here could be

gdf_shp_state.query("state=='ANDAMAN & NICOBAR'")

To select the row(s) where state equals 'ANDAMAN & NICOBAR'

The above is equivalent to:

gdf_shp_state[gdf_shp_state.state == 'ANDAMAN & NICOBAR']