Pymongo 试验

Posted on | Post modified | In | Visitors

首先将 geojson 数据导入到 MongoDB 中，具体操作参考如下。

需要使用两条命令：

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jq --compact-output ".features" input.geojson > output.geojson
mongoimport --db dbname -c collectionname --file "output.geojson" --jsonArray

通过上述命令，我导入了 nyu yellow taxi 的 json 数据。该 json 数据是经过后期处理的，格式如下：

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{
    "type": "FeatureCollection",
    "features": [
        {
            "type": "Feature",
            "properties": {
                "place": "nyu"
            },
            "geometry": {
                "type": "Point",
                "coordinates": [
                    -73.98268127441406,
                    40.731311798095696
                ]
            }
        },
        {
            "type": "Feature",
            "properties": {
                "place": "nyu"
            },
            "geometry": {
                "type": "Point",
                "coordinates": [
                    -73.99224853515625,
                    40.74908065795898
                ]
            }
        },
        ...

比如我想要获得 nyu 南边一个圆里面的所有 taxi 信息。

find 请求如下：

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{geometry: {$geoWithin: { $centerSphere: [ [ -74.0093912556225, 40.7094698471372 ], 0.00008092516322998259 ]}}}

而改写到 pymongo 里面则是：

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import pymongo
import pprint as pp
import json
# Replace XXXX with your connection URI from the Atlas UI

# mongodb:// is the protocol definition
# localhost:27017 is the server we are connecting to
# /myproject is the database we wish to connect to

url = 'mongodb://localhost:27017/m201'
client = pymongo.MongoClient(url)
taxi = client['m201']['nyu_taxi']

query = {
    "geometry": {
        "$geoWithin": {
            "$centerSphere": [
                [ -74.0093912556225, 40.7094698471372 ],
                0.00008092516322998259
            ]
        }
    }
}
projection = {"_id":0}

points = {}
points['type'] = 'FeatureCollection'
points['features'] = []

for t in taxi.find(query,projection):
#     print(t)
    points['features'].append(t)

pp.pprint(points)

# save as geojson format
with open('./filter_nyu_taxi.json', 'w') as outfile:  
    json.dump(points,outfile, indent=4)
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