Python读取JSON遇TypeError：string indices must be integers 求助

问题重现 #

尝试从JSON文件提取title字段时触发如下错误：

Traceback (most recent call last):
  File "C:\Users\2\Desktop\python_work\Chapter 16 - 20\Chapter 16\16.7 Automated Title.py", line 29, in <module>
    title = (eq_data['metadata']['title'])
TypeError: string indices must be integers
[Finished in 661ms]

问题代码片段：

title = ('0')
for eq_data in all_eq_data:
    title = (eq_data['metadata']['title'])

目标JSON数据结构（关键片段）：

"type": "FeatureCollection",
"metadata": {
    "generated": 1550361461000,
    "url": "https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/1.0_day.geojson",
    "title": "USGS Magnitude 1.0+ Earthquakes, Past Day",
    "status": 200,
    "api": "1.7.0",
    "count": 158
}

错误原因 #

all_eq_data是通过json.load(f)加载得到的字典对象，直接遍历字典时，循环变量eq_data会依次取到字典的键名（字符串类型），比如'type'、'metadata'、'features'。此时尝试用eq_data['metadata']去访问，本质是用字符串索引字符串，自然会触发string indices must be integers错误。

而且title字段本身就在all_eq_data['metadata']下，完全不需要循环遍历。

解决方案 #

删除多余的for循环，直接通过字典键路径获取title：

title = all_eq_data['metadata']['title']

修正后的完整代码 #

import json

from plotly.graph_objs import Scattergeo, Layout
from plotly import offline

# Explore the structure of the data.
filename = 'data/eq_data_30_day_m1.json'
with open(filename) as f:
    all_eq_data = json.load(f)

all_eq_dicts = all_eq_data['features']

mags, lons, lats, hover_texts = [], [], [], []
for eq_dict in all_eq_dicts:
    mags.append(eq_dict['properties']['mag'])
    lons.append(eq_dict['geometry']['coordinates'][0])
    lats.append(eq_dict['geometry']['coordinates'][1])
    hover_texts.append(eq_dict['properties']['title'])

# 直接获取title，无需循环
title = all_eq_data['metadata']['title']

# Map the earthquake.
data = [{
    'type': 'scattergeo',
    'lon': lons,
    'lat': lats,
    'text': hover_texts,
    'marker': {
        'size': [3*mag for mag in mags],
        'color': mags,
        'colorscale': 'Viridis',
        'reversescale': True,
        'colorbar': {'title': 'Magnitude'},
    }
}]
my_layout = Layout(title=title)

fig = {'data': data, 'layout': my_layout}
offline.plot(fig, filename='auto_global_earthquakes.html')

内容的提问来源于stack exchange，提问作者KiddoPL