Dates, Times, and Timestamps in Python

The idea

You've already seen datetime in action — the Daily Notes project used it to timestamp every entry.

Now let's look at what it can actually do.

Importing datetime

from datetime import datetime, date, timedelta

The module is called datetime. The main class inside it is also called datetime. Import what you need specifically to keep things clean.

Getting the current date and time

from datetime import datetime

now = datetime.now()
print(now)

Output → 2024-05-06 14:32:45.123456

A datetime object — year, month, day, hour, minute, second, microsecond. All in one.

Access individual parts:

print(now.year)     # 2024
print(now.month)    # 5
print(now.day)      # 6
print(now.hour)     # 14
print(now.minute)   # 32

Formatting — strftime()

strftime() converts a datetime object to a string in any format you want:

from datetime import datetime

now = datetime.now()
print(now.strftime("%Y-%m-%d"))         # 2024-05-06
print(now.strftime("%d/%m/%Y"))         # 06/05/2024
print(now.strftime("%Y-%m-%d %H:%M"))   # 2024-05-06 14:32
print(now.strftime("%A, %d %B %Y"))     # Monday, 06 May 2024

Common format codes:

• %Y — 4-digit year
• %m — month (01–12)
• %d — day (01–31)
• %H — hour 24h (00–23)
• %M — minute (00–59)
• %A — full weekday name
• %B — full month name

Parsing — strptime()

strptime() converts a string into a datetime object — the reverse of strftime():

from datetime import datetime

date_str = "2024-05-06"
dt = datetime.strptime(date_str, "%Y-%m-%d")
print(dt.year)      # 2024
print(dt.month)     # 5

Useful when you read dates from a file or user input and need to work with them as datetime objects.

Date only — date

from datetime import date

today = date.today()
print(today)            # 2024-05-06
print(today.weekday())  # 0 = Monday, 6 = Sunday

Time differences — timedelta

timedelta represents a duration — a difference between two dates or times:

from datetime import date, timedelta

today = date.today()
tomorrow   = today + timedelta(days=1)
last_week  = today - timedelta(days=7)

print(tomorrow)     # 2024-05-07
print(last_week)    # 2024-04-29

You can also subtract two dates to get a timedelta:

from datetime import date

start = date(2024, 1, 1)
end   = date(2024, 5, 6)
diff  = end - start
print(diff.days)    # 126

Heads up!

• The module and the main class have the same name — from datetime import datetime is correct
• strftime() — datetime to string. strptime() — string to datetime
• datetime.now() includes time. date.today() is date only
• Format codes are case-sensitive — %M is minutes, %m is month

What you should understand now

• datetime.now() gives you the current date and time
• strftime() formats a datetime as a string
• strptime() parses a string into a datetime
• date.today() gives you today's date only
• timedelta adds or subtracts days from a date