August 2017
Intermediate to advanced
500 pages
12h 3m
Japanese
Content preview from PythonとJavaScriptではじめるデータビジュアライゼーション
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190
8 章 pandas 入門
def dataframe_to_mongo(df, db_name, collection,\
host='localhost', port=27017,\
username=None, password=None):
""" dataframe
を
mongodb
コレクションに保存する
"""
db = get_mongo_database(db_name, host, port, username,\
password)
records = df.to_dict('records')
db[collection].insert(records)
❶
Mongo
の
_id
フィールドを
DataFrame
に含める。デフォルトでは、この列を削除する。
別の方法でも
DataFrame
を作成できます。ここからは、
Series
から
DataFrame
を構築する方法
を確認し、さらに詳しく調べましょう。
8.6
Series
から
DataFrame
を作成する
pandas
の
Series
での重要な概念はインデックスです。このインデックスは、例えばデータの行
などに含まれる異種データのラベルとして機能します。
pandas
が複数のデータオブジェクトに対
応するときには、このインデックスを使ってフィールドを並べます。
Series
の作成方法は
3
つあります。まずは、
Python
のリストや
NumPy
配列から作成する方法
です。
s = pd.Series([1, 2, 3, 4]) # Series(np.arange(4)) ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.