Python 中关于时间格式的知识点

一：时间，日期，时间戳之间转换

1.将字符串的时间转换为时间戳

a = "2013-10-10 23:40:00"
将其转换为时间数组
import time
timeArray = time.strptime(a, "%Y-%m-%d %H:%M:%S")
转换为时间戳:
timeStamp = int(time.mktime(timeArray))
timeStamp == 1381419600

2.字符格式更改
如a = "2013-10-10 23:40:00",想改为 a = "2013/10/10 23:40:00"
方法:先转换为时间数组,然后转换为其他格式
timeArray = time.strptime(a, "%Y-%m-%d %H:%M:%S")
otherStyleTime = time.strftime("%Y/%m/%d %H:%M:%S", timeArray

3.时间戳转换为指定格式日期:
方法一:
利用localtime()转换为时间数组,然后格式化为需要的格式,如
timeStamp = 1381419600
timeArray = time.localtime(timeStamp)
otherStyleTime = time.strftime("%Y-%m-%d %H:%M:%S", timeArray)
otherStyletime == "2013-10-10 23:40:00"

方法二:
import datetime
timeStamp = 1381419600
dateArray = datetime.datetime.utcfromtimestamp(timeStamp)
otherStyleTime = dateArray.strftime("%Y-%m-%d %H:%M:%S")
otherStyletime == "2013-10-10 23:40:00"

4.获取当前时间并转换为指定日期格式
方法一:
import time
获得当前时间时间戳
now = int(time.time()) ->这是时间戳
转换为其他日期格式,如:"%Y-%m-%d %H:%M:%S"
timeArray = time.localtime(timeStamp)
otherStyleTime = time.strftime("%Y-%m-%d %H:%M:%S", timeArray)

方法二:
import datetime
获得当前时间
now = datetime.datetime.now() ->这是时间数组格式
转换为指定的格式:
otherStyleTime = now.strftime("%Y-%m-%d %H:%M:%S")

5.获得三天前的时间
方法:
import time
import datetime
先获得时间数组格式的日期
threeDayAgo = (datetime.datetime.now() - datetime.timedelta(days = 3))
转换为时间戳:
timeStamp = int(time.mktime(threeDayAgo.timetuple()))
转换为其他字符串格式:
otherStyleTime = threeDayAgo.strftime("%Y-%m-%d %H:%M:%S")
注:timedelta()的参数有:days,hours,seconds,microseconds

6.给定时间戳,计算该时间的几天前时间:
timeStamp = 1381419600
先转换为datetime
import datetime
import time
dateArray = datetime.datetime.utcfromtimestamp(timeStamp)
threeDayAgo = dateArray - datetime.timedelta(days = 3)
参考5,可以转换为其他的任意格式了

7. datetime.strftime(format)，将datetime对象，格式化输出成字符串。

>>> import datetime
>>> dt = datetime.datetime.strptime('201311261010', '%Y%m%d%H%M%S')
>>> dt.strftime('%Y-%m-%d %H:%M:%S')
'2013-11-26 10:01:00'

阿斯顿发

二：判断星期几和最近前后几天：

import datetime
import calendar
from chinese_calendar import is_workday
import pandas as pd

# 判断是否为星期1
def is_monday():
    today = datetime.datetime.now().weekday()
    if today == 0:
        return True

# 判断是否为星期2
def is_tuesday():
    today = datetime.datetime.now().weekday()
    if today == 1:
        return True

# 判断是否为星期3
def is_wednesday():
    today = datetime.datetime.now().weekday()
    if today == 2:
        return True

# 判断是否为星期4
def is_thursday():
    today = datetime.datetime.now().weekday()
    if today == 3:
        return True

# 判断是否为星期5
def is_friday():
    today = datetime.datetime.now().weekday()
    if today == 4:
        return True

# 判断是否为星期6
def is_saturday():
    today = datetime.datetime.now().weekday()
    if today == 5:
        return True

# 判断是否为星期日
def is_sunday():
    today = datetime.datetime.now().weekday()
    if today == 6:
        return True

# 判断上几工作日
def is_word_day(date_num):
    day = datetime.datetime.now() + datetime.timedelta(days=date_num)
    res = is_workday(day)
    if res:
        return day.strftime("%Y-%m-%d")
    else:
        date_num += 1
        return is_word_day(date_num)

# 上一自然日
def up_day():
    return (datetime.datetime.now() + datetime.timedelta(days=-1)).strftime("%Y-%m-%d")

# 获取指定前后天
def get_day(date_num):
    day = datetime.datetime.now() + datetime.timedelta(days=date_num)
    return day.day

# 获取上个月末
def before_month_last_day():
    today = datetime.datetime.now()
    first = datetime.date(day=1, month=today.month, year=today.year)
    last_day = first - datetime.timedelta(days=1)
    return last_day.strftime("%Y%m%d")


# 获取上几工作日
def get_2up_work(up_date=1, is_work=0, date=1):
    '''
    :param up_date:固定参数值
    :param is_work:固定参数值
    :param date:可以用来调整前几天工作日
    :return:
    '''
    day = datetime.datetime.now() + datetime.timedelta(days=-up_date)
    res = is_workday(day)
    if res:
        if is_work == date:
            return day.strftime("%Y%m%d")
        is_work+=1
        up_date+=1
        return get_2up_work(up_date, is_work,date)
    else:
        up_date += 1
        return get_2up_work(up_date, is_work,date)

# 获取上个月初
def before_month_fristday():
    today = datetime.datetime.now()
    if today.month==1:
        first=datetime.date(day=1,month=12,year=today.year-1)
    else:
        first = datetime.date(day=1, month=today.month - 1, year=today.year)
    return first.strftime("%Y%m%d")

# 获取上个星期几
def get_up_day(day=1):
    '''
    :param day: 获取上个星期几，1-7
    :return:
    '''
    cal_dict = {1: calendar.MONDAY, 2: calendar.TUESDAY, 3: calendar.WEDNESDAY, 4: calendar.THURSDAY,
                5: calendar.FRIDAY, 6: calendar.SATURDAY, 7: calendar.SUNDAY}
    date = datetime.datetime.now()
    oneday = datetime.timedelta(days=1)
    while date.weekday() != cal_dict.get(day, calendar.MONDAY):
        date -= oneday
    return date.strftime("%Y%m%d")