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[Python] How to use "datetime" module to process dates

Last Updated on 2021-08-03 by Clay

If we want to processing date and time using Python, the datetime module that comes to minds first. The datetime module encapsulates Python's date-related processing very well, and I have used it a lot in crawlers.

I think the part that I can introduce is divided into three parts:

  • Display date and time
  • Add and subtract actions on the date
  • Change the default output format

If you want to see how the Python official document explains the datetime module, you can directly refer to the official website: https://docs.python.org/zh-cn/3/library/datetime.html

datetime module usage

Let's first look at how to use datetime to display the current date:

import datetime



The datetime module is a native Python module and does not require additional download.

# Display
print('All:', datetime.datetime.now())
print('Year:', datetime.datetime.now().year)
print('Month:', datetime.datetime.now().month)
print('Day:', datetime.datetime.now().day)
print('Weekday:', datetime.datetime.now().weekday())
print('Time:', datetime.datetime.now().time())



Output:

All: 2019-11-07 19:04:57.535884
Year: 2019
Month: 11
Day: 7
Weekday: 3
Time: 19:04:57.535884

We can see from the above code that we can use datetime to print out the current time, which contains four items: year, month, day, time. Of course, we can also print them separately, or print them on the day of the week.

Date calculation

In addition, dates can also be added and subtracted, just use datetime.timedelta().

print('Today:', datetime.datetime.now())
print('Yesterday:', datetime.datetime.now() - datetime.timedelta(days=1))



Output:

Today: 2019-11-07 19:04:57.535884
Yesterday: 2019-11-06 19:04:57.535884

The front is today's date, and the back is our date minus one day. In addition to setting the number of days, we can also increase or decrease the time. (This is very useful in crawlers)

Adjust the output format

In addition, if the time format we deal with is not what we want, we can of course use regular expression to modify it. But the datetime module in Python has already helped you encapsulate the customized output function.

# Format
print('Date:', (datetime.datetime.now() - datetime.timedelta(days=1)).strftime('%Y/%m/%d'))



Output:

Date: 2019/11/06

As you can see, the output format of the current date is the same as we set, which is convenient for us to do later processing.

So the above are some tips on the datetime module in Python.

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