字符串索引必须是整数 geojson

Question

I am trying to extract coordinates from Geojson in Python, when I am trying to extract coordinates from the entire file it is throwing an error "string indices must be integers". But when I am trying to extract single coordinate it runs fine.

Below code gives correct results as [46.931625, -84.52694]

import geojson
with open('output.json') as f:
    gj = geojson.load(f)
features = gj['features'][0]

geometry = features['geometry']
geometry['coordinates']

But When I am trying to run through entire file it throws an error

for feature in gj['features']:
    for geometry in feature['geometry']:
            for coordinates in geometry:
                print(geometry['coordinates'])

sample data is as follows

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "geometry": {
        "type": "Point",
        "coordinates": [
          46.931625,
          -84.52694
        ]
      },
      "properties": {
        "event": "a",
      }
    },
    {
      "type": "Feature",
      "geometry": {
        "type": "Point",
        "coordinates": [
          46.931725,
          -84.52684
        ]
      },
      "properties": {
        "event": "a",
      }
    }
  ]
}

Can you please help me with the error. Thanks in advance.

Answer 1

Well, feature['geometry'] is a dictionary, so the following line will iterate through keys of that dict:

for geometry in feature['geometry']:

You are getting that error since geometry is a key, such as "type" , which is a string. Besides, you don't seem to be using loop variable coordinates anywhere in your code.

Try the following instead:

for feature in gj['features']:
    print(feature["geometry"]['coordinates'])

or better

for feature in gj['features']:
    lat, lon = feature["geometry"]['coordinates']
    print("Lat:", lat, "Lon: ", lon)

This should result in something like

('Lat:', 46.931625, 'Lon: ', -84.52694)
('Lat:', 46.931725, 'Lon: ', -84.52684)

Answer 2

features in your sample is the only array object. Loop through features and get the array of coordinates.

Compressed code:

print([features['geometry']['coordinates'] for features in gj['features']])

This will loop through gj['features'] and print only the features['geometry']['coordinates'] for each of the features.

your script would look like this

import geojson
with open('output.json') as f:
    gj = geojson.load(f)

print([features['geometry']['coordinates'] for features in gj['features']])