How to Use Python Lambda Functions?

 

1. Simple Arithmetic Operations:

add = lambda x, y: x + y

subtract = lambda x, y: x - y

multiply = lambda x, y: x * y

divide = lambda x, y: x / y

​

print(add(3, 5))        # Output: 8

print(subtract(8, 3))    # Output: 5

print(multiply(4, 6))    # Output: 24

print(divide(10, 2))     # Output: 5.0

​

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8

5

24

5.0

2. Sorting a List of Tuples :

pairs = [(1, 5), (2, 3), (4, 1), (3, 8)]

sorted_pairs = sorted(pairs, key=lambda x: x[1])

print(sorted_pairs)  # Output: [(4, 1), (2, 3), (1, 5), (3, 8)]

​

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[(4, 1), (2, 3), (1, 5), (3, 8)]

3. Filtering a List:

numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9]

even_numbers = list(filter(lambda x: x % 2 == 0, numbers))

print(even_numbers)  # Output: [2, 4, 6, 8]

​

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[2, 4, 6, 8]

4. Mapping a Function to a List:

numbers = [1, 2, 3, 4, 5]

squared_numbers = list(map(lambda x: x**2, numbers))

print(squared_numbers)  # Output: [1, 4, 9, 16, 25]

​

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[1, 4, 9, 16, 25]

5. Using Lambda with map and filter:

# Doubling each element in a list using map

​

numbers = [1, 2, 3, 4, 5]

doubled_numbers = list(map(lambda x: x * 2, numbers))

print(doubled_numbers)  # Output: [2, 4, 6, 8, 10]

​

# Filtering odd numbers using filter

​

odd_numbers = list(filter(lambda x: x % 2 != 0, numbers))

print(odd_numbers)  # Output: [1, 3, 5]

​

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[2, 4, 6, 8, 10]

[1, 3, 5]

6. Using Lambda in Key Functions:

# Sorting a list of strings based on the length of each string

words = ['apple', 'banana', 'kiwi', 'orange']

sorted_words = sorted(words, key=lambda x: len(x))

print(sorted_words)  # Output: ['kiwi', 'apple', 'banana', 'orange']

​

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['kiwi', 'apple', 'banana', 'orange']

7. Creating Functions on the Fly:

# Creating a simple calculator with lambda functions

calculator = {

    'add': lambda x, y: x + y,

    'subtract': lambda x, y: x - y,

    'multiply': lambda x, y: x * y,

    'divide': lambda x, y: x / y,

}

​

result = calculator['multiply'](4, 5)

print(result)  # Output: 20

​

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20

8. Using Lambda in List Comprehensions:

# Squaring each element in a list using list comprehension

numbers = [1, 2, 3, 4, 5]

squared_numbers = [(lambda x: x**2)(x) for x in numbers]

print(squared_numbers)  # Output: [1, 4, 9, 16, 25]

​

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[1, 4, 9, 16, 25]

9. Lambda Functions in Higher-Order Functions:

# A higher-order function that takes a function as an argument

def operate_on_numbers(x, y, operation):

    return operation(x, y)

​

# Using a lambda function as an argument

result = operate_on_numbers(10, 5, lambda x, y: x / y)

print(result)  # Output: 2.0

​

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2.0