require 'mongo'
include Mongo
@mongo_client = MongoClient.new("localhost",27017)
@db =  @mongo_client.db('velibdb') 
@stations = @db["stations"]
(75001..75020).each { |arrondissement|
   arr= arrondissement.to_s
   puts arr
   rech = @stations.find({:address => /#{Regexp.quote(arr)}/}).each { |p| 
       id =p['_id']
       @stations.update({:_id => id}, {:$set => {:arrondissement => arrondissement}})     
    }
}

rech = @stations.find({:arrondissement => nil}).each { |p| 
       id =p['_id']
       @stations.update({:_id => id}, {:$set => {:arrondissement => 'banlieue'}})     
    }