Python checking daytime

Question

Basically, I want my script to pause between 4 and 5 AM. The only way to do this I've come up with so far is this:

seconds_into_day = time.time() % (60*60*24)
if 60*60*4 < seconds_into_day < 60*60*5:
    sleep(time_left_till_5am)

Any "proper" way to do this? Aka some built-in function/lib for calculating time; rather than just using seconds all the time?

Answer 1

You want datetime

The datetime module supplies classes for manipulating dates and times in both simple and complex ways

If you use date.hour from datetime.now() you'll get the current hour:

datetimenow = datetime.now();
if datetimenow.hour in range(4, 5)
    sleep(time_left_till_5am)

You can calculate time_left_till_5am by taking 60 - datetimenow.minute multiplying by 60 and adding to 60 - datetimenow.second.

Answer 2

Python has a built-in datetime library: http://docs.python.org/library/datetime.html

This should probably get you what you're after:

import datetime as dt
from time import sleep

now = dt.datetime.now()

if now.hour >= 4 andnow.hour < 5:
    sleep((60 - now.minute)*60 + (60 - now.second))

---

OK, the above works, but here's the purer, less error-prone solution (and what I was originally thinking of but suddenly forgot how to do):

import datetime as dt
from time import sleep

now = dt.datetime.now()
pause = dt.datetime(now.year, now.month, now.day, 4)
start = dt.datetime(now.year, now.month, now.day, 5)

if now >= pause and now < start:
    sleep((start - now).seconds)

That's where my original "timedelta" comment came from -- what you get from subtracting two datetime objects is a timedelta object (which in this case we pull the 'seconds' attribute from).

Answer 3

The following code covers the more general case where a script needs to pause during any fixed window of less than 24 hours duration. Example: must sleep between 11:00 PM and 01:00 AM.

import datetime as dt

def sleep_duration(sleep_from, sleep_to, now=None):
    # sleep_* are datetime.time objects
    # now is a datetime.datetime object
    if now is None:
        now = dt.datetime.now()
    duration = 0
    lo = dt.datetime.combine(now, sleep_from)
    hi = dt.datetime.combine(now, sleep_to)
    if lo <= now < hi:
        duration = (hi - now).seconds
    elif hi < lo:
        if now >= lo:
            duration = (hi + dt.timedelta(hours=24) - now).seconds
        elif now < hi:
            duration = (hi - now).seconds
    return duration

tests = [
    (4, 5, 3, 30),
    (4, 5, 4, 0),
    (4, 5, 4, 30),
    (4, 5, 5, 0),
    (4, 5, 5, 30),
    (23, 1, 0, 0),
    (23, 1, 0, 30),
    (23, 1, 0, 59),
    (23, 1, 1, 0),
    (23, 1, 1, 30),
    (23, 1, 22, 30),
    (23, 1, 22, 59),
    (23, 1, 23, 0),
    (23, 1, 23, 1),
    (23, 1, 23, 59),
    ]

for hfrom, hto, hnow, mnow in tests:
    sfrom = dt.time(hfrom)
    sto = dt.time(hto)
    dnow = dt.datetime(2010, 7, 5, hnow, mnow)
    print sfrom, sto, dnow, sleep_duration(sfrom, sto, dnow)

and here's the output:

04:00:00 05:00:00 2010-07-05 03:30:00 0
04:00:00 05:00:00 2010-07-05 04:00:00 3600
04:00:00 05:00:00 2010-07-05 04:30:00 1800
04:00:00 05:00:00 2010-07-05 05:00:00 0
04:00:00 05:00:00 2010-07-05 05:30:00 0
23:00:00 01:00:00 2010-07-05 00:00:00 3600
23:00:00 01:00:00 2010-07-05 00:30:00 1800
23:00:00 01:00:00 2010-07-05 00:59:00 60
23:00:00 01:00:00 2010-07-05 01:00:00 0
23:00:00 01:00:00 2010-07-05 01:30:00 0
23:00:00 01:00:00 2010-07-05 22:30:00 0
23:00:00 01:00:00 2010-07-05 22:59:00 0
23:00:00 01:00:00 2010-07-05 23:00:00 7200
23:00:00 01:00:00 2010-07-05 23:01:00 7140
23:00:00 01:00:00 2010-07-05 23:59:00 3660

Answer 4

When dealing with dates and times in Python I still prefer mxDateTime over Python's datetime module as although the built-in one has improved greatly over the years it's still rather awkward and lacking in comparison. So if interested go here: mxDateTime It's free to download and use. Makes life much easier when dealing with datetime math.

import mx.DateTime as dt
from time import sleep

now = dt.now()
if 4 <= now.hour < 5:
    stop = dt.RelativeDateTime(hour=5, minute=0, second=0)
    secs_remaining = ((now + stop) - now).seconds
    sleep(secs_remaining)