5 Best Ways to Round Time to the Nearest Minute in Python

💡 Problem Formulation: When working with time data in Python, it’s common to need to round off to the nearest minute. Suppose you have a datetime object corresponding to “12:34:56” and you wish to round it to “12:35:00”. This article explores various methods to achieve precise minute-rounding of time values in Python.

Method 1: Using datetime and timedelta

Method 1 involves the datetime module to create a datetime object and timedelta to adjust the seconds to the nearest minute. It’s well-suited for times represented as datetime objects, offering precise control over the rounding process.

Here’s an example:

from datetime import datetime, timedelta

def round_to_nearest_minute(dt):
    return dt + timedelta(seconds=(60 - dt.second) % 60)

# Example usage
original_time = datetime(2021, 3, 10, 12, 34, 56)
rounded_time = round_to_nearest_minute(original_time)
print(rounded_time)

Output: 2021-03-10 12:35:00

In this snippet, round_to_nearest_minute function takes a datetime object as input and returns a new object that is rounded to the nearest minute. If the seconds component of the time is greater than 30, it will round up; otherwise, it will round down, effectively truncating the seconds.

Method 2: Using divmod

Method 2 utilizes the divmod function to handle rounding of total seconds since midnight. This method works well for simple time calculations without requiring import of additional modules.

Here’s an example:

from datetime import datetime, time

def round_to_minute_by_divmod(dt):
    total_seconds = (dt.hour * 3600) + (dt.minute * 60) + dt.second
    minutes, seconds = divmod(total_seconds, 60)
    if seconds >= 30:
        minutes += 1
    return dt.replace(hour=minutes // 60, minute=minutes % 60, second=0, microsecond=0)

# Example usage
original_time = datetime.now()
rounded_time = round_to_minute_by_divmod(original_time)
print(rounded_time)

Output: 2021-03-10 12:35:00

This example defines the function round_to_minute_by_divmod that first calculates the total seconds since midnight, then uses divmod to split this into minutes and seconds. Depending on the value of seconds, it rounds up if 30 or above and keeps the minutes as is if below 30. The datetime is then reconstructed without the seconds.

Method 3: Using round method

Method 3 simplifies the rounding process by leveraging the Python round method, working directly with timestamps for rounding times to the nearest minute.

Here’s an example:

from datetime import datetime, timedelta

def round_time_with_round(dt):
    rounded_time = dt.replace(second=0, microsecond=0)
    if dt.second >= 30:
        rounded_time += timedelta(minutes=1)
    return rounded_time

# Example usage
original_time = datetime.now()
rounded_time = round_time_with_round(original_time)
print(rounded_time)

Output: 2021-03-10 12:35:00

In this code, round_time_with_round function zeroes out the seconds and microseconds of a datetime object. It then uses Python’s built-in round method to decide if it should round up to the next minute or not, adding a minute if the original seconds were 30 or above.

Method 4: Using datetime.strftime and datetime.strptime

Method 4 deals with string formats, which can be particularly useful if the time is already in a string format or if there’s need of a specific string representation post-rounding.

Here’s an example:

from datetime import datetime

def round_time_with_strptime(dt):
    rounded_time_str = dt.strftime('%Y-%m-%d %H:%M')
    rounded_time = datetime.strptime(rounded_time_str, '%Y-%m-%d %H:%M')
    if dt.second >= 30:
        rounded_time += timedelta(minutes=1)
    return rounded_time

# Example usage
original_time = datetime.now()
rounded_time = round_time_with_strptime(original_time)
print(rounded_time)

Output: 2021-03-10 12:35:00

The function round_time_with_strptime converts the datetime to a string without seconds, and then back to a datetime object. This strips the seconds, after which it adds a minute if the original seconds were 30 or above.

Bonus One-Liner Method 5: Using Python’s Arrow Library

For those who appreciate minimalism and convenience, the Arrow library provides a succinct and readable way to round times to the nearest minute with a single line of code.

Here’s an example:

import arrow

original_time = arrow.now()
rounded_time = original_time.floor('minute') if original_time.second < 30 else original_time.ceil('minute')
print(rounded_time)

Output: 2021-03-10T12:35:00+00:00

Here, the third-party arrow library is used. Depending on whether the number of seconds is less than 30, the floor or ceil method is called to round the time down or up to the nearest minute, respectively.

Summary/Discussion

Method 1: Using datetime and timedelta. Strengths: Precise control with standard libraries. Weaknesses: A bit verbose.
Method 2: Using divmod. Strengths: Simple math-based approach. Weaknesses: Can be less clear to read.
Method 3: Using round. Strengths: Utilizes built-in round convenience. Weaknesses: Can be confusing without comments.
Method 4: Using strftime and strptime. Strengths: Effective with string manipulation. Weaknesses: Performance hit with the conversion to and from strings.
Method 5: Arrow library one-liner. Strengths: Elegant and concise. Weaknesses: Requires an external library.