A lambda function in Python is a small, anonymous function defined using the lambda keyword. Lambda functions are often used when you need a simple function for a short period and don't want to define a full function using the def keyword. Lambda functions are also known as anonymous functions because they don't require a name.
The syntax of a lambda function is as follows:
lambda arguments: expression
Here are some examples of using lambda functions in various scenarios:
Example 1: Basic Lambda Function
# A lambda function that adds two numbers
add = lambda x, y: x + y
result = add(5, 3)
print(result) # Output: 8
Example 2: Sorting with Lambda Function
# A list of tuples containing names and ages
people = [('Alice', 25), ('Bob', 30), ('Charlie', 22)]
# Sort the list based on the second element of each tuple (age)
people_sorted = sorted(people, key=lambda x: x[1])
print(people_sorted)
# Output: [('Charlie', 22), ('Alice', 25), ('Bob', 30)]
Example 3: Using Lambda with map()
# List of numbers
numbers = [1, 2, 3, 4, 5]
# Use lambda with map to square each number
squared_numbers = list(map(lambda x: x**2, numbers))
print(squared_numbers)
# Output: [1, 4, 9, 16, 25]
Example 4: Using Lambda with filter()
# List of numbers
numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
# Use lambda with filter to get even numbers
even_numbers = list(filter(lambda x: x % 2 == 0, numbers))
print(even_numbers)
# Output: [2, 4, 6, 8, 10]
Example 5: Using Lambda in a Custom Function
# A function that generates another function using a lambda function
def power_function(power):
return lambda x: x ** power
square = power_function(2)
cube = power_function(3)
print(square(4)) # Output: 16
print(cube(3)) # Output: 27
Keep in mind that while lambda functions can be convenient for simple operations, using def to define named functions is recommended for more complex operations and for functions that you might need to reuse multiple times.