How to Use Excel's TODAY Function in Pandas

Excel's TODAY function returns the current date, which is useful for tasks ranging from financial projections to date-based filters.

This page explains how to replicate Excel's TODAY function in Python using pandas.

Implementing the Get Current Date function in Pandas#

Here are some common implementations and use cases for the TODAY function in Python and pandas

Retrieve Current Date#

Getting the current date in pandas is straightforward. In Excel, you would use =TODAY(). In Python, use the `datetime` module's `date.today()` method

from datetime import date
current_date = date.today()

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Difference between today and other date#

To calculate the number of days between today and another date, you would use the Excel formula `=TODAY() - A1` where A1 contains a date.

In pandas, you can perform a similar calculation. Notice in the code below that before subtracting the dates, you need to convert the date.today() value to a datetime. This is because the `date.today()` method returns a date object, while the `Datetime` column is a datetime object.

In addition, by default the subtracting two dates in pandas returns a `Timedelta` object, so to get the number of days difference, you can use the `dt.days` attribute.

# Find the number of days between today and the date in the Datetime column
from datetime import date
df['days_since'] = (pd.to_datetime(date.today()) - df['Datetime_Column']).dt.days

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Difference between today and other date#

To calculate the exact amount of time between this exact moment and another date, you would use the Excel formula `=NOW() - A1` where A1 contains a date.

In pandas, you can perform a similar calculation, however, this time, we'll use the `datetime.now()` method, which returns a datetime object, ie: `2023-10-28 12:30:00`.

The result of subtracting two datetimes is a `Timedelta` object, which is displayed in the dataframe like: 299 days 02:40:44.169789. Timedelta objects can be tricky to worth with, but they allow you to access a number of different attributes like: `days`, `seconds`, and `microseconds`.

# Find the exact amount of time between now and the date in the Datetime column
from datetime import datetime
df['time_since'] = (datetime.now() - df['Datetime_Column'])

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Filter dates to today#

Filtering a dataset to show only rows with today's date is a common operation. In Excel, you might use a filter and select today's date.

In pandas, compare the date column with today's date:

# Filter the dataframe to only show rows where the date is today
filtered_df = df[df['Datetime_Column'].dt.date == pd.Timestamp(date.today()).date()]

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Year-to-Date Analysis#

YTD analysis involves analyzing data from the beginning of the current year up to today. In Excel, you might use a combination of filters.

In pandas, create a mask to filter rows from the start of the year to today:

# Filter the dataframe to only show rows where the date is today
# Calculate the start of the year and today's date
start_of_year = pd.Timestamp(date.today().year, 1, 1)
end_of_today = pd.Timestamp(date.today())

# Use the start_of_year and end_of_today variables to filter the dataframe
df = df[(df['Datetime_Column'] >= start_of_year) & (df['Datetime_Column'] <= end_of_today)]

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Common mistakes when using TODAY in Python#

Working with dates in pandas can be confusing. When using Excel's TODAY function in pandas, here are some common mistakes you might run into and how to correct them.

Confusing TODAY with NOW#

In Excel, the `TODAY()` function returns only the date, while `NOW()` returns both the date and time. The same distinction exists in Python.

Avoid using `datetime.now()` when you only need the date. This will give you the current datetime, including hours, minutes, and seconds.

Misunderstanding Output Format#

While Excel's TODAY function outputs in a standard date format, Python's `date.today()` outputs a date object. Users often expect a string output.

To get a formatted string, you can use the `strftime` method on the date object.

# Get the current date in a formatted string
formatted_date = date.today().strftime('%Y-%m-%d')

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Understanding the Get Current Date Formula in Excel#

The TODAY function in Excel doesn't take any arguments and returns the current date.

=TODAY()

Examples