python 时间日期处理汇集

‍#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()