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Adding hours and days to the python datetime

I have a string in the following format
2021-05-06 17:30
How do I convert this to a python datetime and add a certain number of hours (e.g 4 hours)?
I also need to add a certain number of days to the string 2021-05-06

You can first parse the string to a datetime object, and then use a timedelta to add days, hours, etc. to the item.
from datetime import datetime, timedelta
dt = datetime.strptime('2021-05-06 17:30', '%Y-%m-%d %H:%M')
print(dt + timedelta(hours=4))

from datetime import datetime
from datetime import timedelta
origin_date = datetime.strptime("2021-05-06 17:30","%Y-%m-%d %H:%M")
three_hour_later = origin_date + timedelta(hours=3)
print(datetime.strftime(three_hour_later,"%Y-%m-%d %H:%M"))
Please check this link.
https://docs.python.org/3/library/datetime.html

Use the timedelta method available on datetime object to add days, hours, minutes or seconds to the date.
from datetime import datetime, timedelta
additional_hours = 4
additional_days = 2
old_date = datetime.strptime('2021-05-06 17:30', '%Y-%m-%d %H:%M')
new_date = old_date + timedelta(hours=additional_hours, days=additional_days)
print(new_date)

Python - Get Yesterday's date as a string in YYYY-MM-DD format

As an input to an API request I need to get yesterday's date as a string in the format YYYY-MM-DD. I have a working version which is:
yesterday = datetime.date.fromordinal(datetime.date.today().toordinal()-1)
report_date = str(yesterday.year) + \
('-' if len(str(yesterday.month)) == 2 else '-0') + str(yesterday.month) + \
('-' if len(str(yesterday.day)) == 2 else '-0') + str(yesterday.day)
There must be a more elegant way to do this, interested for educational purposes as much as anything else!

You Just need to subtract one day from today's date. In Python datetime.timedelta object lets you create specific spans of time as a timedelta object.
datetime.timedelta(1) gives you the duration of "one day" and is subtractable from a datetime object. After you subtracted the objects you can use datetime.strftime in order to convert the result --which is a date object-- to string format based on your format of choice:
>>> from datetime import datetime, timedelta
>>> yesterday = datetime.now() - timedelta(1)
>>> type(yesterday)
>>> datetime.datetime
>>> datetime.strftime(yesterday, '%Y-%m-%d')
'2015-05-26'
Note that instead of calling the datetime.strftime function, you can also directly use strftime method of datetime objects:
>>> (datetime.now() - timedelta(1)).strftime('%Y-%m-%d')
'2015-05-26'
As a function:
from datetime import datetime, timedelta
def yesterday(frmt='%Y-%m-%d', string=True):
yesterday = datetime.now() - timedelta(1)
if string:
return yesterday.strftime(frmt)
return yesterday
example:
In [10]: yesterday()
Out[10]: '2022-05-13'
In [11]: yesterday(string=False)
Out[11]: datetime.datetime(2022, 5, 13, 12, 34, 31, 701270)

An alternative answer that uses today() method to calculate current date and then subtracts one using timedelta(). Rest of the steps remain the same.
https://docs.python.org/3.7/library/datetime.html#timedelta-objects
from datetime import date, timedelta
today = date.today()
yesterday = today - timedelta(days = 1)
print(today)
print(yesterday)
Output:
2019-06-14
2019-06-13

>>> import datetime
>>> datetime.date.fromordinal(datetime.date.today().toordinal()-1).strftime("%F")
'2015-05-26'

Calling .isoformat() on a date object will give you YYYY-MM-DD
from datetime import date, timedelta
(date.today() - timedelta(1)).isoformat()

I'm trying to use only import datetime based on this answer.
import datetime
oneday = datetime.timedelta(days=1)
yesterday = datetime.date.today() - oneday

Python datetime add

I have a datetime value in string format. How can I change the format from a "-" separated date to a "." separated date. I also need to add 6 hours to let the data be in my time zone.
s = '2013-08-11 09:48:49'
from datetime import datetime,timedelta
mytime = datetime.strptime(s,"%Y-%m-%d %H:%M:%S")
time = mytime.strftime("%Y.%m.%d %H:%M:%S")
dt = str(timedelta(minutes=6*60)) #6 hours
time+=dt
print time
print dt
I get the following result where it adds the six hours at the end and not to the nine:
2013.08.11 09:48:496:00:00
6:00:00

You are adding the string representation of the timedelta():
>>> from datetime import timedelta
>>> print timedelta(minutes=6*60)
6:00:00
Sum datetime and timedelta objects, not their string representations; only create a string after summing the objects:
from datetime import datetime, timedelta
s = '2013-08-11 09:48:49'
mytime = datetime.strptime(s, "%Y-%m-%d %H:%M:%S")
mytime += timedelta(hours=6)
print mytime.strftime("%Y.%m.%d %H:%M:%S")
This results in:
>>> from datetime import datetime, timedelta
>>> s = '2013-08-11 09:48:49'
>>> mytime = datetime.strptime(s, "%Y-%m-%d %H:%M:%S")
>>> mytime += timedelta(hours=6)
>>> print mytime.strftime("%Y.%m.%d %H:%M:%S")
2013.08.11 15:48:49
However, you probably want to use real timezone objects instead, I recommend you use the pytz library:
>>> from pytz import timezone, utc
>>> eastern = timezone('US/Eastern')
>>> utctime = utc.localize(datetime.strptime(s, "%Y-%m-%d %H:%M:%S"))
>>> local_tz = utctime.astimezone(eastern)
>>> print mytime.strftime("%Y.%m.%d %H:%M:%S")
2013.08.11 15:48:49
This will take into account daylight saving time too, for example.

How to add hours to current time in python

I am able to get the current time as below:
from datetime import datetime
str(datetime.now())[11:19]
Result
'19:43:20'
Now, I am trying to add 9 hours to the above time, how can I add hours to current time in Python?

from datetime import datetime, timedelta
nine_hours_from_now = datetime.now() + timedelta(hours=9)
#datetime.datetime(2012, 12, 3, 23, 24, 31, 774118)
And then use string formatting to get the relevant pieces:
>>> '{:%H:%M:%S}'.format(nine_hours_from_now)
'23:24:31'
If you're only formatting the datetime then you can use:
>>> format(nine_hours_from_now, '%H:%M:%S')
'23:24:31'
Or, as #eumiro has pointed out in comments - strftime

Import datetime and timedelta:
>>> from datetime import datetime, timedelta
>>> str(datetime.now() + timedelta(hours=9))[11:19]
'01:41:44'
But the better way is:
>>> (datetime.now() + timedelta(hours=9)).strftime('%H:%M:%S')
'01:42:05'
You can refer strptime and strftime behavior to better understand how python processes dates and time field

This works for me working with seconds not hours and also using a function to convert back to UTC time.
from datetime import timezone, datetime, timedelta
import datetime
def utc_converter(dt):
dt = datetime.datetime.now(timezone.utc)
utc_time = dt.replace(tzinfo=timezone.utc)
utc_timestamp = utc_time.timestamp()
return utc_timestamp
# create start and end timestamps
_now = datetime.datetime.now()
str_start = str(utc_converter(_now))
_end = _now + timedelta(seconds=10)
str_end = str(utc_converter(_end))

This is an answer which is significant for nowadays (python 3.9 or later).
Use strptime to create a datetime object from the timestring. Add 9 hours with timedelta, and match the time format with the timestring you have.
from datetime import datetime, timedelta
from zoneinfo import ZoneInfo
time_format = "%H:%M:%S"
timestring = datetime.strptime(str(datetime.now() + timedelta(hours=9))[11:19], time_format)
#You can then apply custom time formatting as well as a timezone.
TIMEZONE = [Add a timezone] #https://en.wikipedia.org/wiki/List_of_tz_database_time_zones
custom_time_format = "%H:%M"
time_modification = datetime.fromtimestamp(timestring.timestamp(), ZoneInfo(TIMEZONE)).__format__(custom_time_format)
While I think it's more meaningful to apply a timezone, you don't necessarily need to, so you can also simply do that:
time_format = "%H:%M:%S"
timestring = datetime.strptime(str(datetime.now() + timedelta(hours=9))[11:19], time_format)
time_modification = datetime.fromtimestamp(timestring.timestamp())
datetime
https://docs.python.org/3/library/datetime.html
strftime-and-strptime-format-codes
https://docs.python.org/3/library/datetime.html#strftime-and-strptime-format-codes
timedelta
https://docs.python.org/3/library/datetime.html#datetime.timedelta
zoneinfo
https://docs.python.org/3/library/zoneinfo.html#module-zoneinfo

Localizing Epoch Time with pytz in Python

Im working on converting epoch timestamps to dates in different timezones with pytz. What I am trying to do is create a DateTime object that accepts an Olson database timezone and an epoch time and returns a localized datetime object. Eventually I need to answer questions like "What hour was it in New York at epoch time 1350663248?"
Something is not working correctly here:
import datetime, pytz, time
class DateTime:
def __init__(self, timezone, epoch):
self.timezone = timezone
self.epoch = epoch
timezoneobject = pytz.timezone(timezone)
datetimeobject = datetime.datetime.fromtimestamp( self.epoch )
self.datetime = timezoneobject.localize(datetimeobject)
def hour(self):
return self.datetime.hour
if __name__=='__main__':
epoch = time.time()
dt = DateTime('America/Los_Angeles',epoch)
print dt.datetime.hour
dt = DateTime('America/New_York',epoch)
print dt.datetime.hour
This prints the same hour, whereas one should be 3 or so hours ahead. Whats going wrong here? I'm a total Python beginner, any help is appreciated!

datetime.fromtimestamp(self.epoch) returns localtime that shouldn't be used with an arbitrary timezone.localize(); you need utcfromtimestamp() to get datetime in UTC and then convert it to a desired timezone:
from datetime import datetime
import pytz
# get time in UTC
utc_dt = datetime.utcfromtimestamp(posix_timestamp).replace(tzinfo=pytz.utc)
# convert it to tz
tz = pytz.timezone('America/New_York')
dt = utc_dt.astimezone(tz)
# print it
print(dt.strftime('%Y-%m-%d %H:%M:%S %Z%z'))
Or a simpler alternative is to construct from the timestamp directly:
from datetime import datetime
import pytz
# get time in tz
tz = pytz.timezone('America/New_York')
dt = datetime.fromtimestamp(posix_timestamp, tz)
# print it
print(dt.strftime('%Y-%m-%d %H:%M:%S %Z%z'))
It converts from UTC implicitly in this case.

For creating the datetime object belonging to particular timezone from a unix timestamp, you may pass the pytz object as a tz parameter while creating your datetime. For example:
>>> from datetime import datetime
>>> import pytz
>>> datetime.fromtimestamp(1350663248, tz= pytz.timezone('America/New_York'))
datetime.datetime(2012, 10, 19, 12, 14, 8, tzinfo=<DstTzInfo 'America/New_York' EDT-1 day, 20:00:00 DST>)
You can get the list of all timezones using pytz.all_timezones which returns exhaustive list of the timezone names that can be used.
Also take a look at List of tz database time zones wiki.

epochdt = datetime.datetime.fromtimestamp(epoch)
timezone1 = timezone("Timezone/String")
adjusted_datetime = timezone1.localize(epochdt)
Working from memory, so excuse any syntax errors, but that should get you on the right track.
EDIT: Missed the part about knowing the hour,etc. Python has great Time/Date Formatting. At pretty much the bottom of that link is the table showing how to pull different attributes from the datetime object.