lambda

KeywordPython 2.0+Intermediate

Creates a small anonymous (unnamed) function in a single expression

Quick Info

Documentation
Official Docs
Python Version
2.0+

Learn by Difficulty

Easy1 example
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Intermediate1 example
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Advanced1 example
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Expert1 example
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Quick Example

python
square = lambda x: x ** 2
print(square(5))

add = lambda a, b: a + b
print(add(3, 4))

# Lambda with built-in functions
numbers = [5, 2, 8, 1, 9, 3]
print(sorted(numbers))
print(sorted(numbers, key=lambda x: -x))

words = ["banana", "apple", "cherry"]
print(sorted(words, key=lambda w: len(w)))

lambda creates a function in one expression. It is most useful as a key function for sorted(), map(), filter(), etc.

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Tags

languagesyntaxcorefunctionfunctional-programming

Related Items

def
Keyword
Defines a new function or method
map()
Built-in Function
Applies a function to every item in an iterable and returns an iterator
filter()
Built-in Function
Returns elements from an iterable for which a function returns True
sorted()
Built-in Function
Returns a new sorted list from any iterable
functools
Stdlib — Functional
Higher-order functions: lru_cache, partial, reduce, wraps, singledispatch