[英]pymongo to RMongo, mongodb sort query
在pymongo我正在做這樣的排序查詢:
from pymongo import MongoClient
client = MongoClient()
dbase = client[dbname]
collection = dbase[symbol]
start = time.time()
cursor = collection.find().sort([{'_id', -1}]).limit(6000)
data = list(cursor)
現在嘗試在R中做同樣的事情......
library("RMongo")
mongo <- mongoDbConnect("dbname", "localhost", 27017)
query = '{sort({_id: -1})}'
output <- dbGetQuery(mongo, "symbol", query, skip=0, limit=6000)
> output
data frame with 0 columns and 0 rows
這里適當的JSON查詢字符串格式是什么?
用mongolite計算出來....
library('mongolite')
con <- mongo("collection_name", url = "mongodb://localhost:27017/dbname")
output <- con$find('{}', sort='{"_id":-1}', limit=6000)
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