Arbitrary arguments

Intermediate Python for Developers

Jasmin Ludolf

Curriculum Manager

Limitations of defined arguments

def average(values):
    """Find the mean in a sequence of values and round to two decimal places."""

    average_value = sum(values) / len(values)
    rounded_average = round(average_value, 2)
    return rounded_average


# Using six arguments
print(average(15, 29, 4, 13, 11, 8))

TypeError: average() takes 1 positional argument but 6 were given

Arbitrary positional arguments

Docstrings help clarify how to use custom functions
Arbitrary arguments allow functions to accept any number of arguments

# Allow any number of positional, non-keyword arguments
def average(*args):
    # Function code remains the same

Conventional naming: *args
Allows a variety of uses while producing expected results!

Using arbitrary positional arguments

# Calling average with six positional arguments
print(average(15, 29, 4, 13, 11, 8))

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Args create a single iterable

*: Convert arguments to a single iterable (tuple)

# Calculating across multiple lists
print(average(*[15, 29], *[4, 13], *[11, 8]))

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Arbitrary keyword arguments

# Use arbitrary keyword arguments
def average(**kwargs):

    average_value = sum(kwargs.values()) / len(kwargs.values())
    rounded_average = round(average_value, 2)
    return rounded_average

Arbitrary keyword arguments: **kwargs
keyword=value

Using arbitrary keyword arguments

# Calling average with six kwargs
print(average(a=15, b=29, c=4, d=13, e=11, f=8))

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# Calling average with one kwarg
print(average(**{"a":15, "b":29, "c":4, "d":13, "e":11, "f":8}))

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Each key-value pair in the dictionary is mapped to a keyword argument and value!

Kwargs create a single iterable

# Calling average with three kwargs
print(average(**{"a":15, "b":29}, **{"c":4, "d":13}, **{"e":11, "f":8}))

13.33

Let's practice!

Intermediate Python for Developers