How To Standardize Dates In Python

Working with dates is a common task in different programming languages. In Python, it’s common to work with dates to analyze data or handle log files, for instance.

However, different systems and data sources may store dates in different formats, which can be cumbersome when performing date-related operations.

In this tutorial, you will learn how to standardize dates in Python to improve consistency across various data sources and formats using the datetime and dateutil libraries.

Step 1: Install the dateutil library

The dateutil library is not part of the Python standard library. However, it provides powerful extensions to the standard datetime module. To install the dateutil library, you can use the following command:

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pip install python-dateutil

Step 2: Import libraries

Before we start working with dates, let’s import the required libraries by adding the following lines at the beginning of your script:

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import datetime
from dateutil import parser

Step 3: Parse dates using dateutil.parser.parse

The dateutil.parser.parse function can automatically parse dates in different formats and return them as datetime.datetime objects. Here’s an example:

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date_str = "2021-11-25"
date_obj = parser.parse(date_str)
print(date_obj)

Output:

2021-11-25 00:00:00

Let’s try parsing another date format:

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date_str = "25 Nov, 2021"
date_obj = parser.parse(date_str)
print(date_obj)

Output:

2021-11-25 00:00:00

As you can see, the dateutil.parser.parse function can handle different date formats.

Step 4: Formatting dates

After parsing dates, you may want to convert them to a standard format. You can use the strftime method available in the datetime.datetime object to do this. Here is an example:

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formatted_date = date_obj.strftime("%Y-%m-%d")
print(formatted_date)

Output:

2021-11-25

In this example, we have used the format %Y-%m-%d to represent the year, month, and date, respectively. You can use other formats based on your requirements.

Step 5: Standardize dates in a list

Now let’s create a function to standardize dates in a list of strings. The function will take a list of date strings and a format string as arguments, and return a list of formatted date strings:

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def standardize_dates(date_list, date_format="%Y-%m-%d"):
    standardized_dates = []
    for date_str in date_list:
        date_obj = parser.parse(date_str)
        formatted_date = date_obj.strftime(date_format)
        standardized_dates.append(formatted_date)
    return standardized_dates

Here’s how to use the function:

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dates = ["2021-11-25", "25 Nov, 2021", "11/25/2021"]
standardized_dates = standardize_dates(dates)
print(standardized_dates)

Output:

['2021-11-25', '2021-11-25', '2021-11-25']

Full code:

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import datetime
from dateutil import parser
 
def standardize_dates(date_list, date_format="%Y-%m-%d"):
    standardized_dates = []
    for date_str in date_list:
        date_obj = parser.parse(date_str)
        formatted_date = date_obj.strftime(date_format)
        standardized_dates.append(formatted_date)
    return standardized_dates
 
dates = ["2021-11-25", "25 Nov, 2021", "11/25/2021"]
standardized_dates = standardize_dates(dates)
print(standardized_dates)

Conclusion

In this tutorial, you have learned how to standardize dates in Python using the datetime and dateutil libraries. This can be useful when working with data from different sources or performing date-related operations on different date formats.

The dateutil.parser.parse function can automatically identify and parse dates in different formats, making it easy to standardize dates in your Python projects.