A brief introduction of the processing time and the method of realizing the scheduled task in Python3

Regardless of which programming language, time is certainly a very important part, today to see how Python handles time and Python timing tasks, note: This article is the Python3 version of the implementation, in the Python2 version of the implementation of a slightly different, there is time to write another for everyone to distinguish.
1. Calculate Tomorrow and yesterday's date

#! /usr/bin/env python#coding=utf-8# get today, yesterday and tomorrow's date # introduce a datetime module import datetime #计算今天的时间today = Datetime.date.today () # Calculate yesterday's Time yesterday = Today-datetime.timedelta (days = 1) #计算明天的时间tomorrow = today + datetime.timedelta (day = 1) #打印这三个时间pr Int (Yesterday, today, tomorrow)

2. Calculate the last time

Method One:

#! /usr/bin/env python#coding=utf-8# calculates the last time # introduced Datetime,calendar two modules import Datetime,calendar Last_friday = Datetime.date.today () Oneday = Datetime.timedelta (days = 1) while  last_friday.weekday ()! = Calendar. FRIDAY:  Last_friday-= oneday  print (Last_friday.strftime ('%A,%d-%b-%y '))

Method two: Using modulo arithmetic to find the last Friday

#! /usr/bin/env python#coding=utf-8# with modulo operations, you can calculate the number of days to subtract at a time, and the previous Friday # also introduces Datetime,calendar two modules import datetime import Calendar  today = Datetime.date.today () target_day = Calendar. FRIDAY this_day = Today.weekday () Delta_to_target = (this_day-target_day)% 7last_friday = Today-datetime.timedelta (da ys = delta_to_target)  print (Last_friday.strftime ("%d-%b-%y"))

3. Calculate the total playback time of the song

#! /usr/bin/env python#coding=utf-8# Get a list of all the songs in the Play Time and import datetime  def Total_timer (Times):  td = Datetime.timedelta (0)  duration = SUM ([Datetime.timedelta (minutes = m, seconds = s) for M, s in times], TD)  return Duration  times1 = [(2, 3), (    3, 3),    ] Times2 = [(0, 5)    , (+ +), (4,), (1, 10), c11/>]  assert Total_timer (times1) = = Datetime.timedelta (0, 596) assert Total_timer (times2) = = Datetime.timedelta ( 0, 815)  print ("Tests passed.\n" "First  Test total:%s\n"  "Second Test total:%s"% (Total_timer (times1), t Otal_timer (Times2)))

4. Repeatedly execute a command

#! /usr/bin/env python#coding=utf-8# executes a command at the required interval  import time, OS  def re_exe (cmd, inc =): while  true:< C20/>os.system (cmd);   Time.sleep (inc)  Re_exe ("Echo%time%", 5)

5. Scheduled Tasks

#! /usr/bin/env python#coding=utf-8# here need to introduce three modules import time, OS, Sched  # The first parameter determines when a task is returned, returning the number of seconds from a specific time to the present experience # The second parameter measures time in some artificial way schedule = Sched.scheduler (Time.time, Time.sleep)  def perform_command (CMD, Inc):  Os.system (CMD)   def timming_exe (cmd, inc = $):  # Enter is used to schedule the occurrence of an event, starting from now on in nth Seconds  Schedule.enter (inc, 0, Perform_command, (CMD, INC)  # continues to run until the scheduled time queue becomes empty until  schedule.run ()    print ("Show hours after Seconds:") Timming_exe ("Echo%time%", 10)

6. Using Sched to implement periodic calls

#! /usr/bin/env python#coding=utf-8import time, OS, Sched  # The first parameter determines the duration of a task, and returns the number of seconds from a specific time to the present # The second parameter measures time in some artificial way Schedule = Sched.scheduler (Time.time, Time.sleep)  def perform_command (CMD, Inc):  # Schedule an inc second to run itself again, i.e. cycle run  Schedule.enter (inc, 0, Perform_command, (CMD, Inc))  Os.system (cmd)   def timming_exe (cmd, inc =):  # Enter is used to schedule the occurrence of an event, starting from now n seconds start  Schedule.enter (inc, 0, Perform_command, (CMD, Inc))  # Continue running until the scheduled time queue becomes empty  Schedule.run ()    print ("Show Time After Seconds:") Timming_exe ("Echo%time%", 10)

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