119. Lambda Functions in map and filter

Here are 10 Python snippets showcasing the use of lambda functions with map() and filter() for concise transformations:

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1. Doubling Numbers in a List with map()

numbers = [1, 2, 3, 4, 5]
doubled = list(map(lambda x: x * 2, numbers))
print(doubled)  # Output: [2, 4, 6, 8, 10]

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2. Converting a List of Strings to Integers with map()

strings = ["1", "2", "3", "4"]
integers = list(map(lambda x: int(x), strings))
print(integers)  # Output: [1, 2, 3, 4]

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3. Filtering Even Numbers with filter()

numbers = [1, 2, 3, 4, 5, 6]
evens = list(filter(lambda x: x % 2 == 0, numbers))
print(evens)  # Output: [2, 4, 6]

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4. Filtering Strings with a Specific Length

words = ["apple", "bat", "cat", "elephant"]
filtered_words = list(filter(lambda x: len(x) == 3, words))
print(filtered_words)  # Output: ['bat', 'cat']

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5. Mapping to Get Squares of Numbers

numbers = [1, 2, 3, 4, 5]
squares = list(map(lambda x: x ** 2, numbers))
print(squares)  # Output: [1, 4, 9, 16, 25]

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6. Filtering Palindromes

words = ["radar", "hello", "level", "world"]
palindromes = list(filter(lambda x: x == x[::-1], words))
print(palindromes)  # Output: ['radar', 'level']

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7. Combining Two Lists with map()

list1 = [1, 2, 3]
list2 = [4, 5, 6]
summed = list(map(lambda x, y: x + y, list1, list2))
print(summed)  # Output: [5, 7, 9]

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8. Filtering Positive Numbers

numbers = [-10, -5, 0, 5, 10]
positives = list(filter(lambda x: x > 0, numbers))
print(positives)  # Output: [5, 10]

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9. Applying a Conditional Operation with map()

numbers = [1, 2, 3, 4, 5]
processed = list(map(lambda x: x * 2 if x % 2 == 0 else x ** 2, numbers))
print(processed)  # Output: [1, 4, 9, 8, 25]

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10. Filtering and Mapping in a Single Expression

numbers = [1, 2, 3, 4, 5, 6]
processed = list(map(lambda x: x ** 2, filter(lambda x: x % 2 == 0, numbers)))
print(processed)  # Output: [4, 16, 36]