7

I am unable to read a TopoJSON / JSON file in GeoPandas. The issue is that it's a JSON file with keys that are "probably" not standard.

I tried to use the from_features() method but it gives the error: KeyError: 'geometry'

Getting the GeoDataFrame is fine, but it doesn't have the geometry column as one would like.

File Source

File's data structure -

state:  "GA"
stateName:  "Georgia"
voteData:   […]
topojson:   
    type:   "Topology"
    arcs:   […]
    transform:  {…}
    objects:    
        counties:   
            type:   "GeometryCollection"
            geometries: […]
        stateOutline:   {…}
countySummaryStats: {…}

What I tried:

import geopandas as gpd
import pandas as pd
import requests
uri = "https://static01.nyt.com/newsgraphics/2020/10/29/election-early-battlegrounds/030056173a56b8c767e453b62d8cee320984b92d/GA.json"
r = requests.get(uri)
data = r.json()['topojson']['objects']['counties']['geometries']
gpd.GeoDataFrame().from_features(data)

When trying gpd.GeoDataFrame().from_features(r.json()['topojson']['objects']['counties']) I get the error -

TypeError: string indices must be integers

Ideally I'd like to have voteData's fields corresponding to geometries.

Any suggestion how to read this file?

3
  • Can't provide a solution right now but maybe this helps you going: This is indeed a TopoJSON file, not GeoJSON. They both use JSON as general format but have a completely different structure. GeoPandas does not support TopoJSON github.com/geopandas/geopandas/issues/610. Nov 6 '20 at 13:13
  • GeoPandas can read valid TopoJSON via geopandas.read_file('file.json'). It does not support writing. Nov 6 '20 at 13:40
  • Reading itself is the issue here, perhaps because although the file contains TopoJSON data, but it has it in a different format.... problem is that I am very new to GIS so I am not quite familiar with everything yet. Maybe I am wrong and it is indeed a proper TopoJSON, but then the read_file method is not able to parse it properly.
    – jar
    Nov 6 '20 at 13:46
11
+50

The file is not a TopoJSON file. It's just a JSON file containing topojson section. Use the following script.

import geopandas as gpd
import pandas as pd
import json

# read json file
with open('GA.json') as json_file:
    json_data = json.load(json_file)

vote_df = pd.DataFrame(json_data["voteData"])
topo = dict(json_data["topojson"])

# write topojson section to file
with open('topo.json', 'w') as f:
    json.dump(topo, f)

# read as GeoDataFrame
gdf = gpd.GeoDataFrame.from_file('topo.json')
gdf.rename(columns={'NAME': 'county'}, inplace=True)

# add other attributes to gdf
gdf = gdf.merge(vote_df, on='county')
print(gdf)

# OUT:
#      id  ST  GEOID   county STATEFP                          geometry   fips  postal  ....  senate_leading_display        lon        lat 
# 0  None  GA  13001  Appling      13  POLYGON ((-82.43134 31.96647,...   13001     GA  ....              Perdue +56 -82.289024  31.761233 
# 1  None  GA  13007    Baker      13  POLYGON ((-84.63750 31.43408,...   13007     GA  ....               Ossoff +9 -84.448526  31.327343 
# ....
# ....
# [159 rows x 67 columns]


gdf.plot()

enter image description here

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