How do lambda functions work in Python?

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Lambda functions in Python are anonymous, single-expression functions defined using the lambda keyword. Unlike regular functions created with def, lambda functions do not have a name and are typically used for short, simple operations. The basic syntax is:


lambda arguments: expression


For example, a lambda function that adds two numbers looks like this:

add = lambda x, y: x + y
print(add(3, 5)) # Output: 8

Key Features of Lambda Functions:​

1. Single Expression – Lambda functions can only contain one expression, which is evaluated and returned.
2. No Explicit Return – The result is automatically returned without using the return keyword.
3. Used for Short Tasks – They are mostly used when a small function is required for immediate use.
4. Can Be Used with Higher-Order Functions – Lambda functions are commonly used with functions like map(), filter(), and reduce().

Examples of Lambda Functions in Action​

1. Using map() to square a list of numbers:
   python
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   numbers = [1, 2, 3, 4]
   squared = list(map(lambda x: x**2, numbers))
   print(squared) # Output: [1, 4, 9, 16]
2. Using filter() to get even numbers from a list:
   python
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   evens = list(filter(lambda x: x % 2 == 0, numbers))
   print(evens) # Output: [2, 4]
3. Sorting a list of tuples based on the second element:
   python
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   pairs = [(1, 3), (2, 2), (4, 1)]
   sorted_pairs = sorted(pairs, key=lambda x: x[1])
   print(sorted_pairs) # Output: [(4, 1), (2, 2), (1, 3)]

Mastering lambda functions is essential for writing concise, efficient code in Python. If you want to deepen your Python expertise, consider enrolling in a Python certification course to enhance your skills.