python 时间日期处理汇集

2011-03-14 16:52

‍#计算精确时间差

#-----------------------------

# High Resolution Timers

t1=time.clock()

# Do Stuff Here

t2=time.clock()

print t2-t1

# 2.27236813618

# Accuracy will depend on platform and OS,

# but time.clock() uses the most accurate timer it can

time.clock(); time.clock()

# 174485.51365466841

# 174485.55702610247

#-----------------------------

# Also useful;

import timeit

code='[x for x in range(10) if x % 2 == 0]'

eval(code)

# [0, 2, 4, 6, 8]

t=timeit.Timer(code)

print"10,000 repeats of that code takes:",t.timeit(10000),"seconds"

print"1,000,000 repeats of that code takes:",t.timeit(),"seconds"

# 10,000 repeats of that code takes: 0.128238644856 seconds

# 1,000,000 repeats of that code takes:  12.5396490336 seconds

#-----------------------------

import timeit

code='import random; l = random.sample(xrange(10000000), 1000); l.sort()'

t=timeit.Timer(code)

print"Create a list of a thousand random numbers. Sort the list. Repeated a thousand times."

print"Average Time:",t.timeit(1000) /1000

# Time taken: 5.24391507859

‍#time , datetime , string 类型互相转换   

 

# string -> time   

> time.strptime(publishDate,"%Y-%m-%d %H:%M:%S")   

# time -> string  

>time.strftime("%y-%m-%d",t)

#string ->datetime

datetime.strptime(date_string,format) 

#datetime->string

datetime.strftime("%Y-%m-%d %H:%M:%S") 

strptime formating

Directive	Meaning	Notes
%a	Locale’s abbreviated weekday name.
%A	Locale’s full weekday name.
%b	Locale’s abbreviated month name.
%B	Locale’s full month name.
%c	Locale’s appropriate date and time representation.
%d	Day of the month as a decimal number [01,31].
%f	Microsecond as a decimal number [0,999999], zero-padded on the left	-1
%H	Hour (24-hour clock) as a decimal number [00,23].
%I	Hour (12-hour clock) as a decimal number [01,12].
%j	Day of the year as a decimal number [001,366].
%m	Month as a decimal number [01,12].
%M	Minute as a decimal number [00,59].
%p	Locale’s equivalent of either AM or PM.	-2
%S	Second as a decimal number [00,61].	-3
%U	Week number of the year (Sunday as the first day of the week) as a decimal number [00,53]. All days in a new year preceding the first Sunday are considered to be in week 0.	-4
%w	Weekday as a decimal number [0(Sunday),6].
%W	Week number of the year (Monday as the first day of the week) as a decimal number [00,53]. All days in a new year preceding the first Monday are considered to be in week 0.	-4
%x	Locale’s appropriate date representation.
%X	Locale’s appropriate time representation.
%y	Year without century as a decimal number [00,99].
%Y	Year with century as a decimal number.
%z	UTC offset in the form +HHMM or -HHMM (empty string if the the object is naive).	-5
%Z	Time zone name (empty string if the object is naive).
%%	A literal'%'character.

‍#两日期相减  ‍时间差： 

 

d1 = datetime.datetime(2005, 2, 16)  

d2 = datetime.datetime(2004, 12, 31)   

print (d1 - d2).days   

 

starttime = datetime.datetime.now()  

endtime = datetime.datetime.now()  

print (endtime - starttime).seconds  

‍#计算当前时间向后10天的时间。  

#如果是小时 days 换成 hours  

d1 = datetime.datetime.now()  

d3 = d1 + datetime.timedelta(days =10)   

print str(d3)  

print d3.ctime()   

import datetime, calendar  

#昨天

def getYesterday():  

  today=datetime.date.today()  

  oneday=datetime.timedelta(days=1)  

  yesterday=today-oneday   

  return yesterday  

#今天    

def getToday():  

    return datetime.date.today()     

 

#获取给定参数的前几天的日期，返回一个list  

def getDaysByNum(num):  

    today=datetime.date.today()  

    oneday=datetime.timedelta(days=1)      

    li=[]       

    for i in range(0,num):  

        #今天减一天，一天一天减  

        today=today-oneday  

        #把日期转换成字符串  

        #result=datetostr(today)  

        li.append(datetostr(today))  

    return li   

 

#将字符串转换成datetime类型  

def strtodatetime(datestr,format):      

    return datetime.datetime.strptime(datestr,format)  

 

#时间转换成字符串,格式为2008-08-02  

def datetostr(date):    

    return   str(date)[0:10]  

 

#两个日期相隔多少天，例：2008-10-03和2008-10-01是相隔两天  

def datediff(beginDate,endDate):  

    format="%Y-%m-%d";  

    bd=strtodatetime(beginDate,format)  

    ed=strtodatetime(endDate,format)      

    oneday=datetime.timedelta(days=1)  

    count=0

    while bd!=ed:  

        ed=ed-oneday  

        count+=1

    return count  

 

#获取两个时间段的所有时间,返回list  

def getDays(beginDate,endDate):  

    format="%Y-%m-%d";  

    bd=strtodatetime(beginDate,format)  

    ed=strtodatetime(endDate,format)  

    oneday=datetime.timedelta(days=1)   

    num=datediff(beginDate,endDate)+1   

    li=[]  

    for i in range(0,num):   

        li.append(datetostr(ed))  

        ed=ed-oneday  

    return li  

 

#获取当前年份 是一个字符串  

def getYear():  

    return str(datetime.date.today())[0:4]   

 

#获取当前月份 是一个字符串  

def getMonth():  

    return str(datetime.date.today())[5:7]  

 

#获取当前天 是一个字符串  

def getDay():  

    return str(datetime.date.today())[8:10]     

def getNow():  

    return datetime.datetime.now()  

 

      

print getToday()  

print getYesterday()  

print getDaysByNum(3)  

print getDays('2008-10-01','2008-10-05')  

print '2008-10-04 00:00:00'[0:10]  

 

print str(getYear())+getMonth()+getDay()  

print getNow()