我們會(huì)經(jīng)常遇到對(duì)時(shí)間的處理，用python來(lái)進(jìn)行時(shí)間處理簡(jiǎn)直不要太方便了，這一期就給大家介紹一下python的時(shí)間處理！

用python進(jìn)行時(shí)間處理主要會(huì)用到time,calendar,datetime及pandas這幾個(gè)庫(kù),其中又以后兩個(gè)最為常用。

這一期我們主要介紹一下用datetime庫(kù)進(jìn)行時(shí)間處理的常用操作。

1. datetime基礎(chǔ)

1.1 獲取當(dāng)前時(shí)間

import timeimport datetime as dtm## 用datetime獲取當(dāng)前時(shí)間dtime = dtm.datetime.now() # dtm.datetime.utcnow() dtime# datetime.datetime(2018, 12, 15, 13, 1, 30, 200649) # 年、月、日、時(shí)、分、秒、微秒dtime.year, dtime.month, dtime.day# (2018, 12, 15)dtm.datetime.strftime(dtm.datetime.now(), ’%Y-%m-%d %H:%M:%S’)# ’2018-12-15 20:47:45’# 用time庫(kù)獲取當(dāng)前時(shí)間：time.strftime(’%Y-%m-%d %H:%M:%S’, time.localtime(time.time( )))# ’2018-12-15 20:49:17’time.strftime('%Y-%m-%d %H:%M:%S') # ’2018-12-15 20:50:11’

1.2 datetime基本操作

from datetime import datetime, date, time# Using datetime.combine()d = date(2005, 7, 14)t = time(12, 30)datetime.combine(d, t)datetime(2005, 7, 14, 12, 30)# datetime 類的方法：datetime.date()datetime.time()# 可以用str()直接將時(shí)間格式轉(zhuǎn)化為字符串dt = datetime(2005, 7, 14, 12, 30)# datetime(%Y,%m,%d,%H,%M,%S): # datetime共有6個(gè)參數(shù)，分別代表的是年月日時(shí)分秒。其中年月日是必須要傳入的參數(shù)，時(shí)分秒可以不傳入，默認(rèn)全為零。# >>> # Using datetime.timetuple() to get tuple of all attributestt = dt.timetuple()for it in tt: print(it)# 2005 # year# 7 # month# 14 # day# 12 # hour# 30 # minute# 0 # second# 3 # weekday (0 = Monday, 6 = Sunday)# 195 # number of days since 1st January# -1 # dst - method tzinfo.dst() returned None##################################################### 返回今天是周幾x=’2018-05-27’int(dtm.datetime(int(x[ :4]),int(x[5:7]),int(x[8: ])).strftime(’%w’))# 0 表示周日dtm.datetime(2017, 1, 1).strftime('%w') # 0-6 SUN-SAT

2. 時(shí)間戳的轉(zhuǎn)換

Unix時(shí)間戳： Unix 中常常使用一個(gè)數(shù)字記錄時(shí)間，表示距離起始時(shí)間相差的秒數(shù)（根據(jù)系統(tǒng)的精度，時(shí)間單位有時(shí)毫秒，有時(shí)是納秒）。大于 0 表示在起始時(shí)間之后，小于 0 就表示在起始時(shí)間之前。這個(gè)數(shù)字有時(shí)是浮點(diǎn)類型、有時(shí)是整數(shù)類型，但都稱這個(gè)數(shù)字為 Unix 時(shí)間戳（Timestamp）

import timeimport datetime as dtm## 獲取當(dāng)前時(shí)間dtime = dtm.datetime.now() # dtm.datetime.utcnow() # 時(shí)間戳ans_time = int(time.mktime(dtime.timetuple()))ans_time# 1535860540# 時(shí)間戳的轉(zhuǎn)換-1t1 = datetime.datetime.fromtimestamp(ans_time) # local timet1# datetime.datetime(2018, 9, 2, 11, 55, 40)# 也可以用time模塊的localtime()方法： time.localtime(ans_time)# 時(shí)間戳的轉(zhuǎn)換-2t2 = datetime.datetime.utcfromtimestamp(ans_time) # utc timet2# datetime.datetime(2018, 9, 2, 3, 55, 40)t2.strftime('%Y--%m--%d %H:%M:%S')# 2018--09--02 03:55:40# 時(shí)間戳的轉(zhuǎn)換-3pd.to_datetime(ans_time,unit=’s’) # utc time# Timestamp(’2018-09-02 03:55:40’)

3. 時(shí)間格式的轉(zhuǎn)換

strftime 即 string format time，用來(lái)將時(shí)間格式化成字符串 strptime 即 string parse time，用來(lái)將字符串解析成時(shí)間

import datetime as dtmstart = dtm.datetime(2011,1,7,1,21,1) # datetime.datetime(2011, 1, 7, 1, 21, 1)start.strftime(’%Y-%m-%d %H:%M:%S’)# ’2011-01-07 01:21:01’dtm.datetime.strptime(’2011-01-07 01:21:01’,’%Y-%m-%d %H:%M:%S’)# datetime.datetime(2011, 1, 7, 1, 21, 1)str(start)# ’2011-01-07 01:21:01’start.strftime('%Y-%m-%d 00:00:00')# ’2011-01-07 00:00:00’# The strftime method formats a datetime as a string: In [1]: dt.strftime(’%m/%d/%Y %H:%M’)Out[1]: ’10/29/2011 20:30’# Strings can be converted (parsed) into datetime objects using the strptime function: In [2]: dtm.datetime.strptime(’20091031’, ’%Y%m%d’)Out[2]: datetime.datetime(2009, 10, 31, 0, 0)>>> zdtm.datetime(2012, 9, 23, 21, 37, 4, 177393)>>> nice_z = dtm.datetime.strftime(z, ’%A %B %d, %Y’)>>> nice_z’Sunday September 23, 2012’# 字符串形式的時(shí)間格式轉(zhuǎn)化為時(shí)間格式dt = dtm.datetime.strptime('21/11/06 16:30', '%d/%m/%y %H:%M')# 時(shí)間格式轉(zhuǎn)化為字符串# time.strftime( ’%Y-%m-%d’ , time.localtime(time.time()))# >>> # Formatting datetimeprint(dt.strftime('%A, %d. %B %Y %I:%M%p'))# ’Tuesday, 21. November 2006 04:30PM’’The {1} is {0:%d}, the {2} is {0:%B}, the {3} is {0:%I:%M%p}.’.format(dt, 'day', 'month', 'time')# ’The day is 21, the month is November, the time is 04:30PM.’’’’Datetime format specification:%Y Four-digit year%y Two-digit year%m Two-digit month [01, 12] %d Two-digit day [01, 31]%H Hour (24-hour clock) [00, 23]%I Hour (12-hour clock) [01, 12]%M Two-digit minute [00, 59]%S Second [00, 61] (seconds 60, 61 account for leap seconds) %w Weekday as integer [0 (Sunday), 6]

datetime.strptime解析時(shí)間需要輸入相應(yīng)的時(shí)間格式，而dateutil第三方庫(kù)中的parser.parse方法則更加靈活。

dateutil.parser 有時(shí)候也會(huì)有一定的麻煩，比如 ’42’會(huì)被解析為2042 年加上今天的日期：datetime.datetime(2042, 9, 1, 0, 0)

from dateutil.parser import parseparse(’2011-01-03’) # datetime.datetime(2011, 1, 3, 0, 0)parse(’Jan 31, 1997 10:45 PM’) # datetime.datetime(1997, 1, 31, 22, 45)parse(’6/12/2011’, dayfirst=True) # datetime.datetime(2011, 12, 6, 0, 0)# pandas:datestrs = [’2011-07-06 12:00:00’, ’2011-08-06 00:00:00’]pd.to_datetime(datestrs)# DatetimeIndex([’2011-07-06 12:00:00’, ’2011-08-06 00:00:00’], dtype=’datetime64[ns]’, freq=None)

4. Timedelta

timedelta 可以表示兩個(gè)時(shí)間之間的時(shí)間差：

dtm.timedelta(days=0, seconds=0, microseconds=0, milliseconds=0, minutes=0, hours=0, weeks=0)

t1 = dtm.datetime(2018,7,12,15,6,9)t2 = dtm.datetime(2018,9,11,12,33,23)td = t2-t1td# datetime.timedelta(60, 77234) td.days,td.seconds# (60, 77234)# 將timedelta轉(zhuǎn)換為: day, hour, minutedef parse_timedelta(td): ''' transform timedelta to day, hour, minute ''' return td.days, td.seconds//3600, (td.seconds//60)%60parse_timedelta(td)# (60, 21, 27)

利用timedelta進(jìn)行時(shí)間外推：

import datetime as dtm# 100天前的日期(dtm.datetime.now() - dtm.timedelta(days = 100)).strftime('%Y-%m-%d') def TaftD(FORMAT_DATE,i): ''' 返回幾天后的時(shí)間 ''' return (dtm.datetime.strptime(FORMAT_DATE, ’%Y-%m-%d’) + dtm.timedelta(days = i)).strftime(’%Y-%m-%d’)def TaftH(FORMAT_TIME,i): ''' 返回幾小時(shí)后的時(shí)間 ''' return (dtm.datetime.strptime(FORMAT_TIME, ’%Y-%m-%d %H:%M:%S’) + dtm.timedelta(hours = i)).strftime(’%Y-%m-%d %H:%M:%S’)TaftD('2018-05-17', -2)# ’2018-05-15’TaftH('2018-05-17 10:40:00', 2)# ’2018-05-17 12:40:00’

這一期主要介紹了是datetime進(jìn)行時(shí)間處理的一些常用操作，后續(xù)我們會(huì)介紹pandas中的一些時(shí)間處理的操作。歡迎點(diǎn)贊轉(zhuǎn)發(fā)期待哦~

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