有没有人知道pymongo中2dsphere索引的工作示例？

Question

我正在尝试编写一个脚本来执行这里提到的基本的2dsphere索引操作 2dsphere使用pymongo.

我找不到任何例子来弄明白,这是我到目前为止的尝试:

from pymongo import GEOSPHERE
client=MongoClient('localhost',27017)
db=client['dbtest']
points=db['points']
points.create_index([("loc",GEOSPHERE)])
points.insert({"loc":[2 5]})
points.insert({"loc":[30,5]})
more points.insert

for doc in points.find({"loc" : {"$near": { "$geometry" : {"type":"Point","coordinates":[1,2]},"$maxDistance":20}}}):
     print doc

它给出了错误pymongo.errors.OperationFailure: database error: can't find special index: 2d for: { loc: { $near: { $geometry: { type: "Point", coordinates: [ 1, 2 ] }, $maxDistance: 20 } } }

Answer 1

该2dsphere(pymongo.GEOSPHERE)索引类型只能在MongoDB的2.4和更高版本.你也想要为你的积分使用GeoJSON格式.最后,MongoDB的地理查询运算符对顺序敏感,因此在使用$ maxDistance等选项时必须使用SON.以下是使用$ near的示例:

>>> c = pymongo.MongoClient()
>>> points = c.dbtest.points
>>> points.ensure_index([("loc", pymongo.GEOSPHERE)])
u'loc_2dsphere'
>>> points.insert({'loc': {'type': 'Point', 'coordinates': [40, 5]}})
ObjectId('51b0e508fba522160ce84c3a')
>>> for doc in points.find({"loc" : SON([("$near", { "$geometry" : SON([("type", "Point"), ("coordinates", [40, 5])])}), ("$maxDistance", 10)])}):
...     doc
... 
{u'loc': {u'type': u'Point', u'coordinates': [40, 5]}, u'_id': ObjectId('51b0e508fba522160ce84c3a')}

Answer 2

在最近的版本中，我相信$maxDistance必须在$near运算符内部：

from bson.son import SON
from pymongo import MongoClient

db = MongoClient()
latitude = 10
longitude = 20
max_distance = 1000 #meters    

query = {'loc': {'$near': SON([('$geometry', SON([('type', 'Point'), ('coordinates', [longitude, latitude])])), ('$maxDistance', max_distance)])}}

for doc in db.database_name.collection_name.find(query):
    print(doc)