This article introduces Python lambda functions and how write and use them.

Although Python is an object-oriented programming language, lambda functions are handy when you’re doing various kinds of functional programming.

Note: this article will assume you already understand Python programming and how to use a regular function. It’s also assumed you have Python 3.8 or above installed on your device.

Explaining Python Lambda Functions

In Python, functions can take in one or more positional or keyword arguments, a variable list of arguments, a variable list of keyword arguments, and so on. They can be passed into a higher-order function and returned as output. Regular functions can have several expressions and multiple statements. They also always have a name.

A Python lambda function is simply an anonymous function. It could also be called a nameless function. Normal Python functions are defined by the def keyword. Lambda functions in Python are usually composed of the lambda keyword, any number of arguments, and one expression.

Note: the terms lambda functions, lambda expressions, and lambda forms can be used interchangeably, depending on the programming language or programmer.

Lambda functions are mostly used as one-liners. They’re used very often within higher-order functions like map() and filter(). This is because anonymous functions are passed as arguments to higher-order functions, which is not only done in Python programming.

A lambda function is also very useful for handling list comprehension in Python — with various options for using Python lambda expressions for this purpose.

Lambdas are great when used for conditional rending in UI frameworks like Tkinter, wxPython, Kivy, etc. Although the workings of Python GUI frameworks aren’t covered in this article, some code snippets reveal heavy use of lambda functions to render UI based on a user’s interaction.

Things to Understand before Delving into Python Lambda Functions

Because Python is an object-oriented programming language, everything is an object. Python classes, class instances, modules and functions are all handled as objects.

A function object can be assigned to a variable.

It’s not uncommon to assign variables to regular functions in Python. This behavior can also be applied to lambda functions. This is because they’re function objects, even though they’re nameless:

def greet(name):
    return f'Hello {name}'

greetings = greet
greetings('Clint')
>>>>
Hello Clint

Higher-order functions like map(), filter(), and reduce()

It’s likely you’ll need to use a lambda function within built-in functions such as filter() and map(),and also with reduce() — which is imported from the functools module in Python, because it’s not a built-in function. By default, higher-order functions are …….

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