replace(): create a new date or datetime object by replacing specified attributes (such as year, month, or day) with new values

from datetime import datetime
dt = datetime(2019, 12, 31)
print(dt.replace(year=2018, day=14, month=7))

2018-07-14 00:00:00

import datetime
# Year, Month, date, Hour, Minute, Second, microsecond 
dt = datetime.datetime(2019, 12, 31, 23, 59, 59, 345234)
print(dt.replace(day=14))

2019-12-14 23:59:59.345234

Using date object and adding new time part

from datetime import datetime
dt = datetime(2019, 12, 31)
print(dt.replace(year=2018, day=14, month=7, 
                 hour=13, minute=35, second=55, 
                 microsecond=324356))

2018-07-14 13:35:55.324356

from datetime import datetime
dt = datetime(2019, 12, 31)
print(dt.replace())

2019-12-31 00:00:00

Replacing month with invalid date.

from datetime import datetime
dt = datetime(2020, 3, 31)
dt = dt.replace(month=4)
print(dt)

ValueError: day is out of range for month

from datetime import datetime

try:
    dt = datetime(2020, 3, 31)
    dt = dt.replace(month=4)
    print(dt)
except ValueError as my_msg:
    print("This is a ValueError")
    print(my_msg)

This is a ValueError
day is out of range for month

Example 1: Adjusting Time While Keeping the Date Constant

from datetime import datetime

# Original datetime object
original_dt = datetime(2025, 2, 8, 15, 30, 45)
print("Original datetime:", original_dt)

# Replace hour, minute, and second
new_dt = original_dt.replace(hour=10, minute=0, second=0)
print("Updated datetime:", new_dt)

Original datetime: 2025-02-08 15:30:45
Updated datetime: 2025-02-08 10:00:00

Example 2: Setting a Specific Date for Recurring Events

from datetime import datetime

# Original datetime object
original_dt = datetime(2025, 2, 8, 15, 30, 45)
print("Original datetime:", original_dt)

# Replace day to 15th
event_dt = original_dt.replace(day=15)
print("Event datetime:", event_dt)

Original datetime: 2025-02-08 15:30:45
Event datetime: 2025-02-15 15:30:45

Example 3: Handling End-of-Month Dates

from datetime import datetime

# Original datetime object on March 31st
original_dt = datetime(2025, 3, 31)
print("Original datetime:", original_dt)

# Attempt to replace month to February
try:
    new_dt = original_dt.replace(month=2)
    print("Updated datetime:", new_dt)
except ValueError as e:
    print("Error:", e)

Original datetime: 2025-03-31 00:00:00
Error: day is out of range for month

Example 4: Creating a Series of Dates with Modified Attributes

from datetime import datetime, timedelta

# Original datetime object
start_dt = datetime(2025, 1, 1)
print("Start datetime:", start_dt)

# Generate dates with the same time on consecutive days
dates = [start_dt.replace(day=day) for day in range(1, 6)]
for dt in dates:
    print(dt)

Start datetime: 2025-01-01 00:00:00
2025-01-01 00:00:00
2025-01-02 00:00:00
2025-01-03 00:00:00
2025-01-04 00:00:00
2025-01-05 00:00:00

Example 5: Combining `replace()` with Timezone Information

from datetime import datetime, timezone, timedelta

# Original naive datetime object
naive_dt = datetime(2025, 2, 8, 15, 30, 45)
print("Naive datetime:", naive_dt)

# Define UTC+5 timezone
utc_plus_5 = timezone(timedelta(hours=5))

# Replace timezone
aware_dt = naive_dt.replace(tzinfo=utc_plus_5)
print("Timezone-aware datetime:", aware_dt)

Naive datetime: 2025-02-08 15:30:45
Timezone-aware datetime: 2025-02-08 15:30:45+05:00

Subhendu Mohapatra

Author & Instructor at plus2net

I write and maintain practical tutorials on Python, PHP, SQL, JavaScript, HTML, jQuery, and web development at plus2net. The tutorials focus on clear explanations, working examples, and code that readers can test and adapt while learning.

About the author   Watch on YouTube

Connect: