Python datetime cookbook

Table of contents

• Create datetime object without timezone
• Create datetime object with timezone
• Create datetime object of current time
• Create datetime object of same instant with another timezone
• Create datetime object from timestamp
• Create datetime object of same time but yesterday
• Format datetime object to string
• Convert string without timezone to datetime object
• Convert string with UTC offset to datetime object

Create datetime object without timezone

from datetime import datetime

# datetime doesn't support nanosecond
dt1 = datetime(2022, 4, 25, 10, 30, 15, microsecond=500)

Create datetime object with timezone

from datetime import datetime
# ZoneInfo is supported since Python 3.9
from zoneinfo import ZoneInfo

# datetime doesn't support nanosecond
dt1 = datetime(2022, 4, 25, 10, 30, 15, microsecond=500, tzinfo=ZoneInfo('America/New_York'))

Create datetime object of current time

from datetime import datetime
# ZoneInfo is supported since Python 3.9
from zoneinfo import ZoneInfo

# no timezone is set to dt1
dt1 = datetime.now()

# New York timezone is set to dt2
dt2 = datetime.now(ZoneInfo('America/New_York'))

Create datetime object of same instant with another timezone

from datetime import datetime
# ZoneInfo is supported since Python 3.9
from zoneinfo import ZoneInfo

# dt1: 2022-04-25 10:30:15 EDT
dt1 = datetime(2022, 4, 25, 10, 30, 15, 500, ZoneInfo('America/New_York'))

# dt2: 2022-04-25 23:30:15 JST
dt2 = dt1.astimezone(ZoneInfo('Asia/Tokyo'))

Create datetime object from timestamp

import time
from datetime import datetime

current_time = time.time()
dt1 = datetime.fromtimestamp(current_time)

Create datetime object of same time but yesterday

from datetime import datetime, timedelta

# dt1: 2022-04-25 10:30:15 EDT
dt1 = datetime(2022, 4, 25, 10, 30, 15, 500, ZoneInfo('America/New_York'))

# dt2: 2022-04-24 10:30:15 EDT
dt2 = dt1 + timedelta(days=-1)

Format datetime object to string

from datetime import datetime

dt1 = datetime(2022, 4, 25, 10, 30, 15, 500, ZoneInfo('America/New_York'))

# dt_str1: 2022-04-25 10:30:15.000500 EDT
dt_str1 = dt1.strftime('%Y-%m-%d %H:%M:%S.%f %Z')

Convert string without timezone to datetime object

from datetime import datetime

pattern1 = '%Y-%m-%d %H:%M:%S.%f'

dt_str1 = '2022-04-25 10:30:15.000500'
dt1 = datetime.strptime(dt_str1, pattern1)

# if microsecond field has 3 digits only, it will be treated as milliseconds
dt_str2 = '2022-04-25 14:30:15.100'
# dt2: 2022-04-25 14:30:15.100000
dt2 = datetime.strptime(dt_str2, pattern1)

Convert string with UTC offset to datetime object

from datetime import datetime

# Use '%z' to parse utc offset
pattern1 = '%Y-%m-%d %H:%M:%S.%f %z'
dt_str1 = '2022-04-25 10:30:15.000500 -04:00'
dt1 = datetime.strptime(dt_str1, pattern1)