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
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.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.
215
9.4 データのクリーニング
9.4.8
時刻と日付の処理
現 在、
date_of_birth
と
date_of_death
フィールドは文字列で表されています。まず、
Wikipedia
の非公式な編集指針によりさまざまな時間フォーマットが生じています。元の
DataFrame
の最初の
10
個のエントリから、多くの種類のフォーマットがあることがわかります。
df[['name', 'date_of_birth']]
Out[14]:
name date_of_birth
0 César Milstein 8 October 1927
...
2 Vladimir Prelog * July 23, 1906
...
9 Georges Pire 1910-02-10
...
日付フィールドを比較するためには（例えば、出生日から受賞年を引いて受賞者の年齢を求め
る）、演算可能なフォーマットに変換します。当然ながら、
pandas
は面倒な日付と時刻をパースし
てデフォルトで
NumPy
の
datetime64
オブジェクトに変換するのが得意です。
datetime64
には、
たくさんの便利なメソッドや演算子があります。
時間の列を
datetime64
に変換するには、
pandas
の
to_datetime
メソッドを使います。
pd.to_datetime(df.date_of_birth, errors='raise') #
❶
Out:
0 1927-10-08
4 1829-07-26
...
1050 1906-09-06
1051 1931-11-26 ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
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.