使用 Python 从 JSON 嵌套列表和字符串数组中提取值

Question

我正在尝试从马萨诸塞州波士顿的多个街区从 JSON 数据集中提取坐标，但我一直在尝试为每个街区获取第一对坐标城市;下面是 Roslindale 坐标的缩小版。

"features": [{
    "type": "Feature",
    "properties": {
      "Name": "Roslindale",
      "Acres": 1605.5682375,
      "SqMiles": 2.51,
    },
    "geometry": {
      "type": "MultiPolygon",
      "coordinates": [
        [
          [
            [
              -71.125927174853857,
              42.272013107957406
            ],
            [
              -71.125927174853857,
              42.272013107957406
            ]
          ]
        ],
        [
          [
            [
              -71.125830766767592,
              42.272212845889705
            ],
            [
              -71.125830766767592,
              42.272212845889705
            ]
          ]
        ],
        [
          [
            [
              -71.125767203228904,
              42.272315958536389
            ],
            [
              -71.125767203228904,
              42.272315958536389
            ]
          ]
        ]
      ]
    }
  },

现在我已经使用

提取了我想要的数据

for data in boston_neighborhoods:
    neighborhood_name = data['properties']['Name']
    neighborhood_id = data['properties']['Neighborhood_ID']
    neighborhood_size = data['properties']['SqMiles']
    neighborhood_latlon = data['geometry']['coordinates']
    neighborhood_lat = neighborhood_latlon
    neighborhood_lon = neighborhood_latlon

    neighborhoods = neighborhoods.append({'Neighborhood': neighborhood_name,
                                          'Neighborhood_ID': neighborhood_id,
                                          'SqMiles': neighborhood_size,
                                          'Latitude': neighborhood_lat,
                                          'Longitude': neighborhood_lon}, ignore_index=True)

这个 returns 多个坐标对，但我只想要第一对，下面是我现在返回的示例输出：

Latitude                   |           Longitude     
--------------------------------------------------------
[[[[-71.12592717485386,    |    [[[[-71.12592717485386, 
42.272013107957406], [...  |    42.272013107957406], [...

Answer 1

可能有点矫枉过正，但是 JMESPath 使得查询嵌套的 JSON 结构变得非常容易。

向下遍历文档，您首先需要获取数组中的每个元素 ([*])，然后对于每个元素，您将 select 项放入一个对象 (a Python字典）。您将 select properties 下的社区，然后 Name (properties.Name)。您对类似的嵌套属性执行相同的操作。

坐标位于 geometry.coordinates 下，它是坐标对数组的数组。

import jmespath
import pandas as pd

query = """
[*].{ 
    Neighborhood: properties.Name,
    Neighborhood_ID: properties.Neighborhood_ID, 
    SqMiles: properties.SqMiles, 
    Latitude: geometry.coordinates[0][0][0][0], 
    Longitude: geometry.coordinates[0][0][0][1] 
}
"""

compiled = jmespath.compile(query)
result = compiled.search(boston_neighborhoods)

df = pd.DataFrame.from_records(result)
#   Neighborhood Neighborhood_ID  SqMiles   Latitude  Longitude
# 0   Roslindale            None     2.51 -71.125927  42.272013

使用 Python 从 JSON 嵌套列表和字符串数组中提取值

Extract values from JSON nested list and string array with Python

python

json

numpy

pandas

geopandas