Inspecting Keyword Arguments in Pandas CustomBusinessDay Objects

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💡 Problem Formulation: When working with time series data in Python, using the pandas library with CustomBusinessDay objects is quite common for business day calculations. However, users may find themselves needing to inspect the keyword arguments that were used to create a CustomBusinessDay object for debugging or logging purposes. The input is the CustomBusinessDay object, and the desired output is a display of the keyword arguments that have been set within it.

Method 1: Using the vars() Function

The vars() function can be used to return the __dict__ attribute of any object. This dictionary contains all the attributes of the object, including the keyword arguments that were used during its creation. This is useful for debugging or when you want a quick look at the initialization parameters.

Here’s an example:

from pandas.tseries.offsets import CustomBusinessDay

# Create a CustomBusinessDay object with specific keyword arguments
cbd = CustomBusinessDay(weekmask='Sun Mon Tue Wed Thu', holidays=['2023-01-01'])

# Display the keyword arguments
print(vars(cbd))

Output:

{'n': 1, 'normalize': False, 'weekmask': 'Sun Mon Tue Wed Thu', 'holidays': ['2023-01-01'], ...}

The code snippet creates a CustomBusinessDay object with a specific weekmask and holidays. We then print its attributes using the vars() function, allowing us to see the keyword arguments ‘weekmask’ and ‘holidays’ along with their respective values.

Method 2: Accessing Attributes Directly

CustomBusinessDay objects store their initialization parameters as attributes. You can access these attributes directly to retrieve the keyword arguments. This method provides the most straightforward approach if you know the names of the keyword arguments you’re looking for.

Here’s an example:

from pandas.tseries.offsets import CustomBusinessDay

# Create a CustomBusinessDay object with specific keyword arguments
cbd = CustomBusinessDay(holidays=['2023-12-25'])

# Access the keyword arguments directly
weekmask = cbd.weekmask
holidays = cbd.holidays
print('Weekmask:', weekmask)
print('Holidays:', holidays)

Output:

Weekmask: Mon Tue Wed Thu Fri
Holidays: ['2023-12-25']

In this snippet, a CustomBusinessDay object is created with the ‘holidays’ keyword argument. We then access the ‘holidays’ and ‘weekmask’ directly as attributes and print them, displaying the specified holiday and the default weekmask.

Method 3: Using the repr() Function

The repr() function returns a string that would theoretically yield an equivalent object if passed to eval(). For CustomBusinessDay objects, this typically includes the string representation of the keyword arguments. This method is useful for scenarios where an unambiguous string representation is needed for logging or display purposes.

Here’s an example:

from pandas.tseries.offsets import CustomBusinessDay

# Create a CustomBusinessDay object with specific keyword arguments
cbd = CustomBusinessDay(weekmask='Mon Tue Wed Thu Fri', holidays=['2023-12-25'])

# Use repr() to get a string representation including keyword arguments
print(repr(cbd))

Output:

<CustomBusinessDay: weekmask='Mon Tue Wed Thu Fri'>

This snippet demonstrates how to get a string representation of a CustomBusinessDay object that includes keyword arguments, by using the repr() function. Note that not all keyword arguments might be displayed if they are set to default values.

Method 4: Using the __dict__ Attribute

The __dict__ attribute of an object holds its attributes (including methods and keyword arguments) in a dictionary format. Directly accessing this attribute can achieve the same result as Method 1 but with direct syntax.

Here’s an example:

from pandas.tseries.offsets import CustomBusinessDay

# Create a CustomBusinessDay object with specific keyword arguments
cbd = CustomBusinessDay(weekmask='Mon Tue', holidays=['2023-01-01'])

# Access the __dict__ attribute directly
print(cbd.__dict__)

Output:

{'n': 1, 'normalize': False, 'weekmask': 'Mon Tue', 'holidays': ['2023-01-01'], ...}

Here, by directly printing the __dict__ attribute of the CustomBusinessDay object, we obtain a dictionary of all its attributes, including the keyword arguments and their values.

Bonus One-Liner Method 5: Using getattr() with a Default Value

For a one-liner approach, you can use the getattr() function to retrieve a specific attribute by name, with the option to provide a default value if the attribute does not exist. This can be handy for attributes that may or may not be present in the object.

Here’s an example:

from pandas.tseries.offsets import CustomBusinessDay

# Create a CustomBusinessDay object with specific keyword arguments
cbd = CustomBusinessDay()

# Retrieve 'weekmask' keyword argument using getattr()
weekmask = getattr(cbd, 'weekmask', 'Default weekmask not set')
print('Weekmask:', weekmask)

Output:

Weekmask: Mon Tue Wed Thu Fri

This code uses the getattr() function to fetch the ‘weekmask’ attribute of the CustomBusinessDay object, providing a default message in case the object does not have that specific attribute.

Summary/Discussion

  • Method 1: vars(). Simple and Pythonic. Reflects all object attributes. May include more than just keyword arguments.
  • Method 2: Direct Attribute Access. Straightforward. Only useful when you know the names of the attributes. Default values may not be immediately visible.
  • Method 3: repr() Function. Provides an unambiguous string representation. May not contain all keyword arguments if defaults are not modified.
  • Method 4: Direct __dict__ Attribute Access. Similar to Method 1 but more explicit. Can be less readable due to the direct bypass of encapsulation.
  • Bonus: getattr() with Defaults. Compact. Best for accessing a single known attribute with a safety net for non-existence.