Python datetime parsing timestamp with timezone - python-3.x

I ran into this problem a while back ago where parsing an ISO string with time zone data and parsing a timestamp (supposedly of the same time) will give different results. I have written a test to check this behavior and it seems pretty inconsistent:
from pytz import timezone as tz
from datetime import datetime
timezone = "Australia/Sydney"
start_time = "2021-05-04T08:12:00"
tz_object = tz(timezone)
naive_datetime = datetime.fromisoformat(start_time)
zoned_time = datetime(naive_datetime.year, naive_datetime.month, naive_datetime.day, naive_datetime.hour, naive_datetime.minute, naive_datetime.second, tzinfo=tz_object)
parsed_time = datetime.fromtimestamp(zoned_time.timestamp(), tz_object)
assert zoned_time.time() == naive_datetime.time()
assert zoned_time.time() == parsed_time.time()
This test produces the following output
File "test.py", line 13, in <module>
assert zoned_time.time() == parsed_time.time()
AssertionError
Unless I'm missing something I can only conclude that the time resulting from this line
parsed_time = datetime.fromtimestamp(zoned_time.timestamp(), tz_object)
Is producing a different time than parsing the actual ISO string. Typically I'd expect the timestamp from the parsed time return a timestamp referring to 8:12 am in the time zone it was assigned.
Is this behavior expected?
Did I miss something?

With Python 3.9, use zoneinfo. Note that there is a deprecation shim for pytz if required.
Your code then works fine like
from datetime import datetime
from zoneinfo import ZoneInfo
timezone = "Australia/Sydney"
tz_object = ZoneInfo(timezone)
start_time = "2021-05-04T08:12:00"
naive_datetime = datetime.fromisoformat(start_time)
zoned_time = datetime(naive_datetime.year, naive_datetime.month, naive_datetime.day, naive_datetime.hour, naive_datetime.minute, naive_datetime.second, tzinfo=tz_object)
parsed_time = datetime.fromtimestamp(zoned_time.timestamp(), tz_object)
assert zoned_time.time() == naive_datetime.time()
assert zoned_time.time() == parsed_time.time()
As to why you got an assertion error: with pytz you need to localize the datetime object with the time zone; never set a tzinfo directly with pytz.

Related

Python code works in IDE but when compiled in a .exe it doesn't work

I have written a basic program that takes the current internet time and adjusts the system time to be 2 mins ahead. The code can be seen below:
from datetime import timedelta
from datetime import datetime
import win32api
from urllib.request import urlopen
import admin
res = urlopen('http://just-the-time.appspot.com/')
result = res.read().strip()
now = result.decode('utf-8')
new_time = datetime.strptime(now, "%Y-%m-%d %H:%M:%S") + timedelta(hours=0, minutes=2, seconds=0)
year = new_time.year
month = new_time.month
day = new_time.day
hour = new_time.hour
minute = new_time.minute
second = new_time.second
win32api.SetSystemTime(year, month, 0, day, hour, minute, second,0)
print(new_time)
The program works perfectly when using the Pycharm IDE, however when I try to compile the code into an .exe using auto-py-to-exe or pyinstaller, the code runs but no changes are made to the system time. I have tried running as administrator but this doesn't seem to help. Can anyone help?

Is there a way to find the local timezone with datetime?

I am trying to make some code that creates a clock using the user's local time with the datetime library.
import datetime as dt
import os
import time
z = dt.datetime.now()
def local_time():
def time_check(t):
if t < 10:
t = "0{}".format(t)
else:
t = t
return t
p = dt.datetime.now()
hour = p.hour
minute = p.minute
second = p.second
hour = time_check(hour)
minute = time_check(minute)
second = time_check(second)
local_time = '{}:{}:{}'.format(hour, minute, second)
return local_time
time_zone = z.timezone()
for i in range(999999999999999999999):
print("Time: {} {}".format(local_time(), time_zone))
time.sleep(1)
os.system("cls")
What I am doing is gathering the hour, minute, and second of the local time, and constantly updating it in the terminal, and deleting the previous time.
This works fine, but I am also trying to display the timezone of the user, and I am having a hard time trying to find a way to do it. Does anyone know a way? Thanks.
Importing the python-dateutil library should make this easier. Install the library with the pip install python-dateutil command at the terminal if you don't have it installed beforehand. Once you do that, test the below code:
from datetime import *
from dateutil.tz import *
print(datetime.now(tzlocal()).tzname())
print(datetime(2021, 6, 2, 16, 00, tzinfo=tzlocal()).tzname())
#Output
#SA Western Standard Time
#SA Western Standard Time
Using tzlocal() and tzname() together will give you the current timezone. The dateutil library is very powerful and useful. Check out the full documentation HERE.
Hopefully that helped.

Convert UTC timezone to IST python

The following code line gives me the UTC timing on the production server.
timestamp = datetime.datetime.now().strftime('%Y-%m-%d %H:%M:%S.%f')
Please suggest a way to convert above UTC timezone to IST(Indian Standard Time) timing.
datetime.now() gives you a naive datetime object that represents local time according to the setting of the machine you run the script on (which in this case just happens to be UTC since it's a server). See the docs.
To get "now" in a specific timezone, you can set the tz property appropriately.
Python >= 3.9: you have zoneinfo in the standard lib to do this:
from zoneinfo import ZoneInfo
dtobj = datetime.now(tz=ZoneInfo('Asia/Kolkata'))
print(dtobj)
>>> 2020-07-23 11:11:43.594442+05:30
Python < 3.9: I'd recommend the dateutil package to do so (or use zoneinfo via backports.zoneinfo).
from datetime import datetime
from dateutil.tz import gettz
dtobj = datetime.now(tz=gettz('Asia/Kolkata'))
print(dtobj)
>>> 2020-07-23 11:08:54.032651+05:30
from datetime import datetime
import pytz
tz_NY = pytz.timezone('Asia/Kolkata')
datetime_NY = datetime.now(tz_NY)
print("India time:", datetime_NY.strftime("%Y-%m-%d %H:%M:%S.%f"))
>>India time: 2021-05-03 12:25:21.877976

Inconsistent datetime object in Python3 and Django2

Python 3, Django 2
I am trying to get a function to consistently return a datetime object.
Here are the conditions where it does and does not work.
I have a function that generates a datetime object with an offset like so:
from django.conf import settings
from datetime import datetime
def off_time():
date = datetime.now()
offset = settings.TIME_OFFSET
offtime = date + offset
return offtime
TIME_OFFSET is generated in settings thus:
from datetime import timedelta
TIME_OFFSET = timedelta(days=370000)
If I save to a model object like this:
from django.db import models
import stellar.physics_tools
class Test(models.Model):
cdate = models.DateTimeField(default=stellar.physics_tools.off_time, help_text='When Generated')
and then work on the cdate, I can do this:
cdate = test.cdate
creation_date = cdate.strftime("%d-%m-%Y %H:%M:%S")
and it works ok.
but if I try this:
newtime = stellar.physics_tools.off_time
return newtime.strftime("%d-%m-%Y %H:%M:%S")
I get:
'function' object has no attribute 'strftime'
I need this function to return an object that I can use .strftime on, at least.
Any help appreciated. Thanks.
For this to work I need to call the function with () like this:
newtime = stellar.physics_tools.off_time()
I was not doing this because if I did this in the Django model construction it returns the value created when the class is defined, which is not what I want.
In short I still need to use stellar.physics_tools.off_time in the Django model, but when calling the function outside of this I need to use stellar.physics_tools.off_time().

Python string time [duplicate]

How can I run a function in Python, at a given time?
For example:
run_it_at(func, '2012-07-17 15:50:00')
and it will run the function func at 2012-07-17 15:50:00.
I tried the sched.scheduler, but it didn't start my function.
import time as time_module
scheduler = sched.scheduler(time_module.time, time_module.sleep)
t = time_module.strptime('2012-07-17 15:50:00', '%Y-%m-%d %H:%M:%S')
t = time_module.mktime(t)
scheduler_e = scheduler.enterabs(t, 1, self.update, ())
What can I do?
Reading the docs from http://docs.python.org/py3k/library/sched.html:
Going from that we need to work out a delay (in seconds)...
from datetime import datetime
now = datetime.now()
Then use datetime.strptime to parse '2012-07-17 15:50:00' (I'll leave the format string to you)
# I'm just creating a datetime in 3 hours... (you'd use output from above)
from datetime import timedelta
run_at = now + timedelta(hours=3)
delay = (run_at - now).total_seconds()
You can then use delay to pass into a threading.Timer instance, eg:
threading.Timer(delay, self.update).start()
Take a look at the Advanced Python Scheduler, APScheduler: http://packages.python.org/APScheduler/index.html
They have an example for just this usecase:
http://packages.python.org/APScheduler/dateschedule.html
from datetime import date
from apscheduler.scheduler import Scheduler
# Start the scheduler
sched = Scheduler()
sched.start()
# Define the function that is to be executed
def my_job(text):
print text
# The job will be executed on November 6th, 2009
exec_date = date(2009, 11, 6)
# Store the job in a variable in case we want to cancel it
job = sched.add_date_job(my_job, exec_date, ['text'])
Might be worth installing this library: https://pypi.python.org/pypi/schedule, basically helps do everything you just described. Here's an example:
import schedule
import time
def job():
print("I'm working...")
schedule.every(10).minutes.do(job)
schedule.every().hour.do(job)
schedule.every().day.at("10:30").do(job)
schedule.every().monday.do(job)
schedule.every().wednesday.at("13:15").do(job)
while True:
schedule.run_pending()
time.sleep(1)
Here's an update to stephenbez' answer for version 3.5 of APScheduler using Python 2.7:
import os, time
from apscheduler.schedulers.background import BackgroundScheduler
from datetime import datetime, timedelta
def tick(text):
print(text + '! The time is: %s' % datetime.now())
scheduler = BackgroundScheduler()
dd = datetime.now() + timedelta(seconds=3)
scheduler.add_job(tick, 'date',run_date=dd, args=['TICK'])
dd = datetime.now() + timedelta(seconds=6)
scheduler.add_job(tick, 'date',run_date=dd, kwargs={'text':'TOCK'})
scheduler.start()
print('Press Ctrl+{0} to exit'.format('Break' if os.name == 'nt' else 'C'))
try:
# This is here to simulate application activity (which keeps the main thread alive).
while True:
time.sleep(2)
except (KeyboardInterrupt, SystemExit):
# Not strictly necessary if daemonic mode is enabled but should be done if possible
scheduler.shutdown()
I've confirmed the code in the opening post works, just lacking scheduler.run(). Tested and it runs the scheduled event. So that is another valid answer.
>>> import sched
>>> import time as time_module
>>> def myfunc(): print("Working")
...
>>> scheduler = sched.scheduler(time_module.time, time_module.sleep)
>>> t = time_module.strptime('2020-01-11 13:36:00', '%Y-%m-%d %H:%M:%S')
>>> t = time_module.mktime(t)
>>> scheduler_e = scheduler.enterabs(t, 1, myfunc, ())
>>> scheduler.run()
Working
>>>
I ran into the same issue: I could not get absolute time events registered with sched.enterabs to be recognized by sched.run. sched.enter worked for me if I calculated a delay, but is awkward to use since I want jobs to run at specific times of day in particular time zones.
In my case, I found that the issue was that the default timefunc in the sched.scheduler initializer is not time.time (as in the example), but rather is time.monotonic. time.monotonic does not make any sense for "absolute" time schedules as, from the docs, "The reference point of the returned value is undefined, so that only the difference between the results of consecutive calls is valid."
The solution for me was to initialize the scheduler as
scheduler = sched.scheduler(time.time, time.sleep)
It is unclear whether your time_module.time is actually time.time or time.monotonic, but it works fine when I initialize it properly.
dateSTR = datetime.datetime.now().strftime("%H:%M:%S" )
if dateSTR == ("20:32:10"):
#do function
print(dateSTR)
else:
# do something useful till this time
time.sleep(1)
pass
Just looking for a Time of Day / Date event trigger:
as long as the date "string" is tied to an updated "time" string, it works as a simple TOD function. You can extend the string out to a date and time.
whether its lexicographical ordering or chronological order comparison,
as long as the string represents a point in time, the string will too.
someone kindly offered this link:
String Comparison Technique Used by Python
had a really hard time getting these answers to work how i needed it to,
but i got this working and its accurate to .01 seconds
from apscheduler.schedulers.background import BackgroundScheduler
sched = BackgroundScheduler()
sched.start()
def myjob():
print('job 1 done at: ' + str(dt.now())[:-3])
dt = datetime.datetime
Future = dt.now() + datetime.timedelta(milliseconds=2000)
job = sched.add_job(myjob, 'date', run_date=Future)
tested accuracy of timing with this code:
at first i did 2 second and 5 second delay, but wanted to test it with a more accurate measurement so i tried again with 2.55 second delay and 5.55 second delay
dt = datetime.datetime
Future = dt.now() + datetime.timedelta(milliseconds=2550)
Future2 = dt.now() + datetime.timedelta(milliseconds=5550)
def myjob1():
print('job 1 done at: ' + str(dt.now())[:-3])
def myjob2():
print('job 2 done at: ' + str(dt.now())[:-3])
print(' current time: ' + str(dt.now())[:-3])
print(' do job 1 at: ' + str(Future)[:-3] + '''
do job 2 at: ''' + str(Future2)[:-3])
job = sched.add_job(myjob1, 'date', run_date=Future)
job2 = sched.add_job(myjob2, 'date', run_date=Future2)
and got these results:
current time: 2020-12-10 19:50:44.632
do job 1 at: 2020-12-10 19:50:47.182
do job 2 at: 2020-12-10 19:50:50.182
job 1 done at: 2020-12-10 19:50:47.184
job 2 done at: 2020-12-10 19:50:50.183
accurate to .002 of a second with 1 test
but i did run a lot of tests and accuracy ranged from .002 to .011
never going under the 2.55 or 5.55 second delay
#everytime you print action_now it will check your current time and tell you should be done
import datetime
current_time = datetime.datetime.now()
current_time.hour
schedule = {
'8':'prep',
'9':'Note review',
'10':'code',
'11':'15 min teabreak ',
'12':'code',
'13':'Lunch Break',
'14':'Test',
'15':'Talk',
'16':'30 min for code ',
'17':'Free',
'18':'Help ',
'19':'watever',
'20':'watever',
'21':'watever',
'22':'watever'
}
action_now = schedule[str(current_time.hour)]

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