CODEWITHSUNDEEP
pythondatetime
t0mmyt
t0mmyt

Reputation: 513

What was midnight yesterday as an epoch time?

I'm trying to get my head around the datetime module. I know the time now as an epoch and the time an event last happened (as an epoch time). What I need to do is figure out whether that event happened between midnight and midnight of yesterday.

t = time.time() # is now
t2 = 1234567890 # some arbitrary time from my log

24 hours ago is t - 86400, but how can I round that up and down to midnight. I'm having real trouble finding a way to get timestamps in and out of datetime or then manipulating a datetime to set the time.

Upvotes: 30

Views: 33699

Answers (8)

Steven Buehler
Steven Buehler

Reputation: 11

For python3:

from datetime import datetime, timedelta

now = datetime.now()
today = datetime(now.year,now.month,now.day)
yesterday = today - timedelta(days=1)

then, for epoch timestamps:

today_epoch = today.timestamp()
yesterday_epoch = yesterday.timestamp()

The function datetime.today() still returns the current time like now() does.

Upvotes: 0

carton.swing
carton.swing

Reputation: 1707

To get the specific timezone's midnight timestamp:

from datetime import datetime
import pytz

TZ = "Asia/Shanghai"
datetime.now(pytz.timezone(TZ)).replace(hour=0, minute=0, second=0, microsecond=0).timestamp()

Upvotes: 2

Pedro Lobito
Pedro Lobito

Reputation: 98921

import time

start_str = time.strftime( "%m/%d/%Y" ) + " 00:00:00"
end_str = time.strftime( "%m/%d/%Y ") + " 23:59:59"
start_ts = int( time.mktime( time.strptime( start_str, "%m/%d/%Y %H:%M:%S" ) ) )
end_ts = int( time.mktime( time.strptime( end_str, "%m/%d/%Y %H:%M:%S" ) ) )

print (start_ts) # timestamp today at 00:00:00
print (end_ts) # timestamp today at 23:59:59
# 1552435200
# 1552521599

Source Python get unix epoch for today’s midnight and today’s 23:59:59 (start of day, end of day)

Upvotes: 0

ggemmill
ggemmill

Reputation: 69

Midnight at the start of today is:

midnight = (int(time.time() // 86400)) * 86400

so yesterday's midnight is:

midnight = (int(time.time() // 86400)) * 86400 - 86400

Upvotes: 5

mastisa
mastisa

Reputation: 2073

You can use this code:

import time

seconds_of_day = 24 * 60 * 60  # 86400
last_midnight = (round(time.time()) // seconds_of_day) * seconds_of_day
yesterday_last_midnight = last_midnight - seconds_of_day

Upvotes: 0

Martijn Pieters
Martijn Pieters

Reputation: 1121992

In the Middle of the Night

Generating the last midnight is easy:

from datetime import datetime, time

midnight = datetime.combine(datetime.today(), time.min)

That combines today's date (you can use date() or a datetime() instance, your pick), together with time.min to form a datetime object at midnight.

Yesterday

With a timedelta() you can calculate the previous midnight:

from datetime import timedelta

yesterday_midnight = midnight - timedelta(days=1)

That Was Yesterday

Now test if your timestamp is in between these two points:

timestamp = datetime.fromtimestamp(some_timestamp_from_your_log)
if yesterday_midnight <= timestamp < midnight:
    # this happened between 00:00:00 and 23:59:59 yesterday

All Together Now

Combined into one function:

from datetime import datetime, time, timedelta

def is_yesterday(timestamp):
    midnight = datetime.combine(datetime.today(), time.min)
    yesterday_midnight = midnight - timedelta(days=1)
    return yesterday_midnight <= timestamp < midnight:

if is_yesterday(datetime.fromtimestamp(some_timestamp_from_your_log)):
    # ...

Upvotes: 71

Bill Bell
Bill Bell

Reputation: 21643

In my estimation, many date and time manipulations are easier to do, and to understand, using the arrow library. This is one of them.

Create an arbitrary date and time.

>>> import arrow
>>> arbitrary = arrow.get(2017,8,16,11,5)

Calculate midnight_yesterday: first, midnight of arbitrary as its 'day' floor; then shift this back by one day. Display the result.

>>> midnight_yesterday = arbitrary.floor('day').shift(days=-1)
>>> midnight_yesterday 
<Arrow [2017-08-15T00:00:00+00:00]>

Use timestamp for the desired overall result, for Python 3.3+.

>>> midnight_yesterday.datetime.timestamp()
1502755200.0

Or use this expression for Python 2.7. (Credit: https://stackoverflow.com/a/11743262/131187 for the latter two expressions.)

>>> (midnight_yesterday-arrow.get(1970,1,1)).total_seconds()
1502755200.0

Upvotes: 0

chepner
chepner

Reputation: 531175

Given such a timestamp, you can use divmod to compute the number of days since the epoch (which you don't care about), and how many seconds are leftover (which you do):

days_since, remaining_seconds = divmod(t, 24*3600)  # Divide by number of seconds in one day

Then, you subtract the leftover seconds from your original timestamp, which produces midnight of the current day.

t -= remaining_seconds

Rounding up is as simple as shifting your target timestamp forward exactly one day before rounding down.

tomorrow_t = t + 24 * 3600
days_since, remaining_seconds = divmod(tomorrow_t, 24*3600)
t = tomorrow_t - remaining_seconds

Upvotes: 2

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