Lambda Functions in Python
A Python Lambda Function is a tiny, unnamed function that can take any number of inputs but only one expression. A Python Lambda Function doesn’t need a name like a regular function defined using the def keyword. This makes it great for quick tasks where a full function declaration isn’t needed.
What is a function in Python?
People commonly call a Python Lambda Function an “anonymous function” because it doesn’t have a name. When you want to make a function that you may use more than once in regular Python programming, you use the def keyword. But there are many times when you only require a small piece of logic for a one-time task, like sorting a list or filtering data.
Python lambda functions are based on the idea of giving you a “disposable” logic unit. People often use them as parameters for higher-order functions like map(), filter(), and reduce(). You may keep your code short and avoid adding functions that are only used once to your namespace by utilizing a lambda.
The syntax for Python lambda functions
You need to know how to use the python lambda function syntax before you can develop good code. The structure is simple on purpose:
lambda arguments: expression
How the Syntax Works:
- The Keyword: The lambda keyword starts every definition.
- Arguments: These are the things you give to the function. You can have no arguments, one argument, or more than one argument.
- The Colon: This is what separates the input variables from the operation.
- The Expression: This is the logic that runs. The answer to this question is given automatically.
- Important rule: A lambda function can only have one expression. You can’t put more than one line of code, words like “pass,” or complicated loops inside a lambda.
Using Python Lambda Function with More Than One Argument
A lot of beginners think that anonymous functions can only take one input. But for arithmetic and data processing, it’s important to use the python lambda function with more than one argument.
You can do operations with more than one variable on the same line by using commas between the inputs. This is very helpful in geometry or when using libraries like Pandas to cope with data that has more than one column.
For example: Finding the area of a shape
You can send two arguments (length and width) into a single lambda to find the area of a rectangle.
# Area of a rectangle in Python with more than one argument
calculate_area = lambda length, width: length * width
print(calculate_area(10, 5))
# Output: 50
In this case, length and width are the two inputs for the Python lambda function, and the expression after the colon does the multiplication.
Using Python Lambda Functions If Else Logic
You can still make decisions with Python’s ternary operator, even if a lambda can only have one expression. This lets you put conditional logic right into your anonymous function.
The format for a python lambda function if else is:
value_if_true if x is true if condition else value_if_false
For example, putting numbers into groups
Let’s say you want to see if a number is “Even” or “Odd.” You can use a lambda instead of writing a four-line def function.
Python # Find out if a number is even or odd.
check_even = lambda num: “Even” if num % 2 == 0 otherwise “Odd”
print(check_even(7))
# Output: Odd
Using Python’s lambda function with if-else logic is great for cleaning and validating data, but you shouldn’t nest more than one if-else statement because it makes the code hard to comprehend.
Examples of Useful Python Lambda Functions
Using built-in functional tools in python lambda function examples is the best approach to learn how these functions work. With these tools, you can work with lists and dictionaries with very little code.
- Using Filter() with Lambda
The filter() function takes items out of a list that meet a given condition.
Python # Getting numbers that are bigger than 10: numbers = [2, 15, 8, 22, 5] greater_than_ten = list(filter(lambda x: x > 10, numbers))
print(greater_than_ten) # Output: [15, 22]
- Using Map() with Lambda
The map() method does something to each item in a list.
Python # nums = [1, 2, 3, 4] then squaring each integer in the list
squared_nums = list(map(lambda x: x**2, nums))
print(squared_nums) # The output is [1, 4, 9, 16]
- Using Sort() with Lambda
You can use a lambda to set your own sorting rules, such sorting a list of strings by the final letter of each string.
names = [“Apple”, “Banana”, “Cherry”] in Python.sort(key=lambda x: x[-1])
print(names) # Output: [‘Banana’, ‘Apple’, ‘Cherry’]
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FAQs
Q1. What is the main difference between a Python Lambda Function and a normal function?
A Python Lambda Function doesn’t have a name and can only have one expression. A regular function (def) has a name, can be used again, and can have more than one line of complicated logic.
Q2. Can I use more than one parameter with a Python lambda function?
Yes. You can pass as many arguments as you like by putting commas between them. For example, lambda a, b, c: a + b + c.
Q3. Can you utilize the python lambda function if you use complicated logic?
You can use the ternary operator for simple if-else reasoning, but you should stay away from circumstances that are too complex or nested. If the logic needs elif, it’s best to use a regular def function.
Q4. Where do people most often use python lambda functions?
Functional programming and data science use them the most, especially in the map(), filter(), reduce(), and sorting techniques.
Q5. What does it mean to label them “anonymous” functions?
Anonymous functions don’t have a name identifier as regular functions do, which is why they are called that. They are normally set up where they are going to be used.