Date Manipulation in Python

This article explains date manipulation in Python.

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Date Manipulation in Python

Date manipulation in Python primarily uses the datetime module. This module provides various classes and functions to manipulate dates and times.

Below are some examples of basic date manipulation using the datetime module.

Getting Date and Time

You can get the current date and time as follows. datetime.now() and datetime.today() return almost the same result, but there can be differences in how they handle time zones.

1from datetime import datetime
2
3# Get the current date and time
4now = datetime.now()
5print(f"Current date and time: {now}")
6
7# Get today's date only
8today = datetime.today()
9print(f"Today's date: {today.date()}")

• This code retrieves and displays the current date and time, as well as just today's date.

Creating Specific Dates and Times

You can create a specific date and time as follows.

1from datetime import datetime
2
3# Create a specific date and time
4specific_date = datetime(2023, 11, 7, 10, 30, 45)
5print(f"Specified date and time: {specific_date}")

• This code creates and displays the specified date and time (November 7, 2023, 10:30:45).

Formatting Dates

Date formatting can be done as follows.

1from datetime import datetime
2
3now = datetime.now()
4
5# Format the date
6formatted_date = now.strftime("%Y-%m-%d %H:%M:%S")
7print(f"Formatted date and time: {formatted_date}")

• This code gets the current date and time, formats it to the specified format using strftime, and displays it.

Date format strings

• %Y: Year (4 digits)
• %m: Month (01 to 12)
• %d: Day (01 to 31)
• %H: Hour (00 to 23)
• %M: Minute (00 to 59)
• %S: Second (00 to 59)

Parsing date strings

You can convert a string representing a date into a datetime object.

1from datetime import datetime
2
3date_string = "2023-11-07 10:30:45"
4parsed_date = datetime.strptime(date_string, "%Y-%m-%d %H:%M:%S")
5print(f"Parsed date and time: {parsed_date}")

• This code converts a date represented as a string into a datetime object using strptime() and displays it.

Date Arithmetic

Date arithmetic can be performed as follows.

 1from datetime import datetime, timedelta
 2
 3now = datetime.now()
 4
 5# Date for one day later
 6tomorrow = now + timedelta(days=1)
 7print(f"Date for one day later: {tomorrow}")
 8
 9# Date for one week ago
10last_week = now - timedelta(weeks=1)
11print(f"Date for one week ago: {last_week}")
12
13# Time for two hours later
14in_two_hours = now + timedelta(hours=2)
15print(f"Time for two hours later: {in_two_hours}")

• This code uses timedelta to add or subtract days and times from the current date and time, calculating and displaying the date and time for tomorrow, one week ago, and two hours later.

Handling time zones

You can also handle time zones with the datetime module.

 1from datetime import datetime, timezone, timedelta
 2
 3# Current UTC time
 4utc_now = datetime.now(timezone.utc)
 5print(f"Current UTC time: {utc_now}")
 6
 7# JST (UTC+9)
 8jst = timezone(timedelta(hours=9))
 9jst_now = datetime.now(jst)
10print(f"Current JST time: {jst_now}")

• datetime returns a 'naive datetime' (without timezone information) by default. You can explicitly handle time zones by using the timezone class or zoneinfo.

The date class and time class

With the datetime module, you can also handle only dates or only times.

1from datetime import date, time
2
3d = date(2023, 11, 7)
4t = time(10, 30, 45)
5
6print(f"Date only: {d}")
7print(f"Time only: {t}")

• The date class handles only dates, and the time class handles only times.

Conversion between datetime and timestamp

Conversion between UNIX timestamps and datetime objects is possible. Here, a UNIX timestamp refers to the number of seconds elapsed since January 1, 1970.

 1from datetime import datetime
 2
 3now = datetime.now()
 4
 5# datetime → timestamp
 6timestamp = now.timestamp()
 7print(f"Timestamp: {timestamp}")
 8
 9# timestamp → datetime
10restored = datetime.fromtimestamp(timestamp)
11print(f"Restored datetime: {restored}")

• This code converts the current date and time to a UNIX timestamp, then uses the fromtimestamp() function to convert that timestamp back to a datetime object.

Common pitfalls

When using the datetime module, you should be aware of the following points.

• datetime.now() does not consider time zones, so for internationalization, you need to explicitly use timezone.utc.
• Be careful not to confuse %m (month) and %M (minute) in format strings.

Summary

The datetime module also provides many other features for flexible date and time manipulation. Additionally, classes like date, time, and timedelta are available, specialized for specific operations.

Using other libraries also enables more advanced date manipulation. For example, pandas specializes in handling time series data, while dateutil is suitable for complex date parsing. Also, the arrow library is useful too.

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