将带有嵌套列表的Geo json转换为pandas数据框 [英] Convert Geo json with nested lists to pandas dataframe

问题描述

我以这种形式拥有一个巨大的geo json:

I've a massive geo json in this form:

 {'features': [{'properties': {'MARKET': 'Albany',
    'geometry': {'coordinates': [[[-74.264948, 42.419877, 0],
       [-74.262041, 42.425856, 0],
       [-74.261175, 42.427631, 0],
       [-74.260384, 42.429253, 0]]],
     'type': 'Polygon'}}},
  {'properties': {'MARKET': 'Albany',
    'geometry': {'coordinates': [[[-73.929627, 42.078788, 0],
       [-73.929114, 42.081658, 0]]],
     'type': 'Polygon'}}},
  {'properties': {'MARKET': 'Albuquerque',
    'geometry': {'coordinates': [[[-74.769198, 43.114089, 0],
       [-74.76786, 43.114496, 0],
       [-74.766474, 43.114656, 0]]],
     'type': 'Polygon'}}}],
 'type': 'FeatureCollection'}

阅读json后:

import json
with open('x.json') as f:
    data = json.load(f)

我将值读入列表，然后读入数据框:

I read the values into a list and then into a dataframe:

#to get a list of all markets
mkt=set([f['properties']['MARKET'] for f in data['features']])

#to create a list of market and associated lat long
markets=[(market,list(chain.from_iterable(f['geometry']['coordinates']))) for f in data['features'] for market in mkt if f['properties']['MARKET']==mkt]

df = pd.DataFrame(markets[0:], columns=['a','b'])     

df的前几行是:

      a       b
0   Albany  [[-74.264948, 42.419877, 0], [-74.262041, 42.4...
1   Albany  [[-73.929627, 42.078788, 0], [-73.929114, 42.0...
2   Albany  [[-74.769198, 43.114089, 0], [-74.76786, 43.11...

然后要取消嵌套b列中的嵌套列表，我使用了pandas concat:

Then to unnest the nested list in column b, I used pandas concat:

df1 = pd.concat([df.iloc[:,0:1], df['b'].apply(pd.Series)], axis=1)

但这将创建包含许多NaN的8070列.有没有一种方法可以将所有经纬度按市场分组(列a)?希望有一百万行乘两列的数据帧.

But this is creating 8070 columns with many NaNs. Is there a way to group all the latitudes and longitudes by the Market (column a)? A million rows by two column dataframe is desired.

期望的操作是:

mkt         lat         long 
Albany      42.419877   -74.264948
Albany      42.078788   -73.929627
..
Albuquerque  35.105361   -106.640342

请注意，列表元素中的零([-74.769198，43.114089，0])需要忽略.

Pls note that the zero in the list element ([-74.769198, 43.114089, 0]) needs to be ignored.

推荐答案

类似这样的东西?

from pandas.io.json import json_normalize
df = json_normalize(geojson["features"])

coords = 'properties.geometry.coordinates'

df2 = (df[coords].apply(lambda r: [(i[0],i[1]) for i in r[0]])
           .apply(pd.Series).stack()
           .reset_index(level=1).rename(columns={0:coords,"level_1":"point"})
           .join(df.drop(coords,1), how='left')).reset_index(level=0)

df2[['lat','long']] = df2[coords].apply(pd.Series)

df2

输出:

   index  point properties.geometry.coordinates properties.MARKET  \
0      0      0         (-74.264948, 42.419877)            Albany   
1      0      1         (-74.262041, 42.425856)            Albany   
2      0      2         (-74.261175, 42.427631)            Albany   
3      0      3         (-74.260384, 42.429253)            Albany   
4      1      0         (-73.929627, 42.078788)            Albany   
5      1      1         (-73.929114, 42.081658)            Albany   
6      2      0         (-74.769198, 43.114089)       Albuquerque   
7      2      1          (-74.76786, 43.114496)       Albuquerque   
8      2      2         (-74.766474, 43.114656)       Albuquerque   

  properties.geometry.type        lat       long  
0                  Polygon -74.264948  42.419877  
1                  Polygon -74.262041  42.425856  
2                  Polygon -74.261175  42.427631  
3                  Polygon -74.260384  42.429253  
4                  Polygon -73.929627  42.078788  
5                  Polygon -73.929114  42.081658  
6                  Polygon -74.769198  43.114089  
7                  Polygon -74.767860  43.114496  
8                  Polygon -74.766474  43.114656 

如果:

geojson = {'features': [{'properties': {'MARKET': 'Albany',
    'geometry': {'coordinates': [[[-74.264948, 42.419877, 0],
       [-74.262041, 42.425856, 0],
       [-74.261175, 42.427631, 0],
       [-74.260384, 42.429253, 0]]],
     'type': 'Polygon'}}},
  {'properties': {'MARKET': 'Albany',
    'geometry': {'coordinates': [[[-73.929627, 42.078788, 0],
       [-73.929114, 42.081658, 0]]],
     'type': 'Polygon'}}},
  {'properties': {'MARKET': 'Albuquerque',
    'geometry': {'coordinates': [[[-74.769198, 43.114089, 0],
       [-74.76786, 43.114496, 0],
       [-74.766474, 43.114656, 0]]],
     'type': 'Polygon'}}}],
 'type': 'FeatureCollection'}

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