實用又強大，6 款 Python 時間&日期庫推薦

在使用 Python 的開發過程當中，除了使用 datetime 標準庫來處理時間和日期，還有許多第三方的開源庫值得嘗試。

一、Arrow

Arrow 是一個專門處理時間和日期的輕量級 Python 庫，它提供了一種合理、智能的方式來建立、操做、格式化、轉換時間和日期，並提供了一個支持許多常見構建方案的智能模塊 API 。簡單來講，它能夠幫你以更簡便的操做和更少的代碼來使用日期和時間。其設計靈感主要來源於 moment.js 和 requests 。

Quick start

$ pip install arrow

>>> import arrow
>>> utc = arrow.utcnow()
>>> utc
<Arrow [2013-05-11T21:23:58.970460+00:00]>

>>> utc = utc.replace(hours=-1)
>>> utc
<Arrow [2013-05-11T20:23:58.970460+00:00]>

>>> local = utc.to('US/Pacific')
>>> local
<Arrow [2013-05-11T13:23:58.970460-07:00]>

>>> arrow.get('2013-05-11T21:23:58.970460+00:00')
<Arrow [2013-05-11T21:23:58.970460+00:00]>

>>> local.timestamp
1368303838

>>> local.format()
'2013-05-11 13:23:58 -07:00'

>>> local.format('YYYY-MM-DD HH:mm:ss ZZ')
'2013-05-11 13:23:58 -07:00'

>>> local.humanize()
'an hour ago'

>>> local.humanize(locale='ko_kr')
'1시간 전'

二、Delorean

Delorean 提供了一個相比於 datetime 和 pytz 的更好的抽象，讓你處理時間更容易。它有不少有用的處理時區的特性，標準化時區或者從一個時區改變到另一個時區。

Quick start

from datetime import datetime
import pytz

est = pytz.timezone('US/Eastern')
d = datetime.now(pytz.utc)
d = est.normalize(d.astimezone(est))
return d

from delorean import Delorean

d = Delorean()
d = d.shift('US/Eastern')
return d

三、Pendulum

原生的 datetime 足夠應付基本狀況，但當面對更復雜的用例時，一般會有的捉襟見肘，不那麼直觀。 Pendulum 在標準庫的基礎之上，提供了一個更簡潔，更易於使用的 API ，旨在讓 Python datetime 更好用。

Quick start

>>> import pendulum

>>> now_in_paris = pendulum.now('Europe/Paris')
>>> now_in_paris
'2016-07-04T00:49:58.502116+02:00'

# Seamless timezone switching
>>> now_in_paris.in_timezone('UTC')
'2016-07-03T22:49:58.502116+00:00'

>>> tomorrow = pendulum.now().add(days=1)
>>> last_week = pendulum.now().subtract(weeks=1)

>>> if pendulum.now().is_weekend():
...     print('Party!')
'Party!'

>>> past = pendulum.now().subtract(minutes=2)
>>> past.diff_for_humans()
>>> '2 minutes ago'

>>> delta = past - last_week
>>> delta.hours
23
>>> delta.in_words(locale='en')
'6 days 23 hours 58 minutes'

# Proper handling of datetime normalization
>>> pendulum.create(2013, 3, 31, 2, 30, 0, 0, 'Europe/Paris')
'2013-03-31T03:30:00+02:00' # 2:30 does not exist (Skipped time)

# Proper handling of dst transitions
>>> just_before = pendulum.create(2013, 3, 31, 1, 59, 59, 999999, 'Europe/Paris')
'2013-03-31T01:59:59.999999+01:00'
>>> just_before.add(microseconds=1)
'2013-03-31T03:00:00+02:00'

四、dateutil

dateutil 是 datetime 標準庫的一個擴展庫，幾乎支持以全部字符串格式對日期進行通用解析，日期計算靈活，內部數據更新及時。

Quick start

>>> from dateutil.relativedelta import *
>>> from dateutil.easter import *
>>> from dateutil.rrule import *
>>> from dateutil.parser import *
>>> from datetime import *
>>> now = parse("Sat Oct 11 17:13:46 UTC 2003")
>>> today = now.date()
>>> year = rrule(YEARLY,dtstart=now,bymonth=8,bymonthday=13,byweekday=FR)[0].year
>>> rdelta = relativedelta(easter(year), today)
>>> print("Today is: %s" % today)
Today is: 2003-10-11
>>> print("Year with next Aug 13th on a Friday is: %s" % year)
Year with next Aug 13th on a Friday is: 2004
>>> print("How far is the Easter of that year: %s" % rdelta)
How far is the Easter of that year: relativedelta(months=+6)
>>> print("And the Easter of that year is: %s" % (today+rdelta))
And the Easter of that year is: 2004-04-11

五、moment

用於處理日期/時間的 Python 庫，設計靈感一樣是來源於 moment.js 和 requests ，設計理念源自 Times Python 模塊。

Usage

import moment
from datetime import datetime

# Create a moment from a string
moment.date("12-18-2012")

# Create a moment with a specified strftime format
moment.date("12-18-2012", "%m-%d-%Y")

# Moment uses the awesome dateparser library behind the scenes
moment.date("2012-12-18")

# Create a moment with words in it
moment.date("December 18, 2012")

# Create a moment that would normally be pretty hard to do
moment.date("2 weeks ago")

# Create a future moment that would otherwise be really difficult
moment.date("2 weeks from now")

# Create a moment from the current datetime
moment.now()

# The moment can also be UTC-based
moment.utcnow()

# Create a moment with the UTC time zone
moment.utc("2012-12-18")

# Create a moment from a Unix timestamp
moment.unix(1355875153626)

# Create a moment from a Unix UTC timestamp
moment.unix(1355875153626, utc=True)

# Return a datetime instance
moment.date(2012, 12, 18).date

# We can do the same thing with the UTC method
moment.utc(2012, 12, 18).date

# Create and format a moment using Moment.js semantics
moment.now().format("YYYY-M-D")

# Create and format a moment with strftime semantics
moment.date(2012, 12, 18).strftime("%Y-%m-%d")

# Update your moment's time zone
moment.date(datetime(2012, 12, 18)).locale("US/Central").date

# Alter the moment's UTC time zone to a different time zone
moment.utcnow().timezone("US/Eastern").date

# Set and update your moment's time zone. For instance, I'm on the
# west coast, but want NYC's current time.
moment.now().locale("US/Pacific").timezone("US/Eastern")

# In order to manipulate time zones, a locale must always be set or
# you must be using UTC.
moment.utcnow().timezone("US/Eastern").date

# You can also clone a moment, so the original stays unaltered
now = moment.utcnow().timezone("US/Pacific")
future = now.clone().add(weeks=2)

六、When.py

提供對用戶很是友好的特性來幫助執行常見的日期和時間操做。

Usage