Python Lambda Functions

Introduction to Lambda Functions

Python lambda functions are small, anonymous functions defined with the lambda keyword. They are typically used for creating small, one-time-use functions that can be used wherever function objects are required. A lambda function can take any number of arguments, but it can only have one expression. The result of this expression is returned automatically.

Syntax of Lambda Functions

The syntax of a lambda function is:

lambda arguments: expression

Unlike regular functions defined with def, lambda functions are limited to a single expression. They are syntactically restricted to a single line, but semantically function similarly to regular functions.

Using Lambda Functions with map()

The map() function in Python applies a given function to all items in an input list (or any other iterable) and returns a map object (an iterator). Lambda functions are often used with map() to apply a simple operation to every element of an iterable.

Using Lambda Functions with filter()

The filter() function constructs an iterator from elements of an iterable for which a function returns true. Lambda functions are useful here to define the filtering criteria.

Limitations of Lambda Functions

Lambda functions have some limitations. They can only contain expressions, not statements, and they cannot include annotations or default arguments. This simplicity makes them less suitable for complex functions, but perfect for small, concise operations.