WORKING WITH DATES

Python provides a rich set of date-related functions. Listing 1.7 displays the content of the script date_time2.py that displays various date-related values, such as the current date and time; the day of the week, month, and year; and the time in seconds since the epoch.

LISTING 1.7: date_time2.py

import time
import datetime

print("Time in seconds since the epoch: %s" %time.time())
print("Current date and time: " , datetime.datetime.now())
print("Or like this: " ,datetime.datetime.now().strftime("%y-%m-%d-%H-%M"))

print("Current year: ", datetime.date.today().strftime("%Y"))
print("Month of year: ", datetime.date.today().strftime("%B"))
print("Week number of the year: ", datetime.date.today().strftime("%W"))
print("Weekday of the week: ", datetime.date.today().strftime("%w"))
print("Day of year: ", datetime.date.today().strftime("%j"))
print("Day of the month : ", datetime.date.today().strftime("%d"))
print("Day of week: ", datetime.date.today().strftime("%A"))

Listing 1.8 displays the output generated by running the code in Listing 1.7.

LISTING 1.8 datetime2.out

Time in seconds since the epoch: 1375144195.66
Current date and time:  2013-07-29 17:29:55.664164
Or like this:  13-07-29-17-29
Current year:  2013
Month of year:  July
Week number of the year:  30
Weekday of the week:  1
Day of year:  210
Day of the month :  29
Day of week:  Monday

Python allows you to perform arithmetic calculates with date-related values, as shown in the following code block:

>>> from datetime import timedelta
>>> a = timedelta(days=2, hours=6)
>>> b = timedelta(hours=4.5)
>>> c = a + b
>>> c.days
2
>>> c.seconds
37800
>>> c.seconds / 3600
10.5
>>> c.total_seconds() / 3600
58.5

Converting Strings to Dates

Listing 1.9 displays the content of string2date.py that illustrates how to convert a string to a date, and also how to calculate the difference between two dates.

LISTING 1.9: string2date.py

from datetime import datetime

text = '2014-08-13'
y = datetime.strptime(text, '%Y-%m-%d')
z = datetime.now()
diff = z - y
print('Date difference:',diff)

The output from Listing 1.9 is shown here:

Date difference: -210 days, 18:58:40.197130