python - 如何将数据从 mongodb 导入到 pandas？

Question

我在 mongodb 的集合中有大量数据需要分析。如何将这些数据导入 pandas？

我是 pandas 和 numpy 的新手。

编辑: mongodb 集合包含带有日期和时间标记的传感器值。传感器值是 float 据类型。

样本数据:

{
"_cls" : "SensorReport",
"_id" : ObjectId("515a963b78f6a035d9fa531b"),
"_types" : [
    "SensorReport"
],
"Readings" : [
    {
        "a" : 0.958069536790466,
        "_types" : [
            "Reading"
        ],
        "ReadingUpdatedDate" : ISODate("2013-04-02T08:26:35.297Z"),
        "b" : 6.296118156595,
        "_cls" : "Reading"
    },
    {
        "a" : 0.95574014778624,
        "_types" : [
            "Reading"
        ],
        "ReadingUpdatedDate" : ISODate("2013-04-02T08:27:09.963Z"),
        "b" : 6.29651468650064,
        "_cls" : "Reading"
    },
    {
        "a" : 0.953648289182713,
        "_types" : [
            "Reading"
        ],
        "ReadingUpdatedDate" : ISODate("2013-04-02T08:27:37.545Z"),
        "b" : 7.29679823731148,
        "_cls" : "Reading"
    },
    {
        "a" : 0.955931884300997,
        "_types" : [
            "Reading"
        ],
        "ReadingUpdatedDate" : ISODate("2013-04-02T08:28:21.369Z"),
        "b" : 6.29642922525632,
        "_cls" : "Reading"
    },
    {
        "a" : 0.95821381,
        "_types" : [
            "Reading"
        ],
        "ReadingUpdatedDate" : ISODate("2013-04-02T08:41:20.801Z"),
        "b" : 7.28956613,
        "_cls" : "Reading"
    },
    {
        "a" : 4.95821335,
        "_types" : [
            "Reading"
        ],
        "ReadingUpdatedDate" : ISODate("2013-04-02T08:41:36.931Z"),
        "b" : 6.28956574,
        "_cls" : "Reading"
    },
    {
        "a" : 9.95821341,
        "_types" : [
            "Reading"
        ],
        "ReadingUpdatedDate" : ISODate("2013-04-02T08:42:09.971Z"),
        "b" : 0.28956488,
        "_cls" : "Reading"
    },
    {
        "a" : 1.95667927,
        "_types" : [
            "Reading"
        ],
        "ReadingUpdatedDate" : ISODate("2013-04-02T08:43:55.463Z"),
        "b" : 0.29115237,
        "_cls" : "Reading"
    }
],
"latestReportTime" : ISODate("2013-04-02T08:43:55.463Z"),
"sensorName" : "56847890-0",
"reportCount" : 8
}

Answer 1

pymongo 可能会帮助您，以下是我正在使用的一些代码:

import pandas as pd
from pymongo import MongoClient


def _connect_mongo(host, port, username, password, db):
    """ A util for making a connection to mongo """

    if username and password:
        mongo_uri = 'mongodb://%s:%s@%s:%s/%s' % (username, password, host, port, db)
        conn = MongoClient(mongo_uri)
    else:
        conn = MongoClient(host, port)


    return conn[db]


def read_mongo(db, collection, query={}, host='localhost', port=27017, username=None, password=None, no_id=True):
    """ Read from Mongo and Store into DataFrame """

    # Connect to MongoDB
    db = _connect_mongo(host=host, port=port, username=username, password=password, db=db)

    # Make a query to the specific DB and Collection
    cursor = db[collection].find(query)

    # Expand the cursor and construct the DataFrame
    df =  pd.DataFrame(list(cursor))

    # Delete the _id
    if no_id:
        del df['_id']

    return df