Python Anonymous/Lambda Function
What are lambda functions in Python?
In Python, anonymous function is a function that is defined without a name.
While normal functions are defined using the
def keyword, in Python anonymous functions are defined using the lambda keyword.
Hence, anonymous functions are also called lambda functions.
How to use lambda Functions in Python?
A lambda function in python has the following syntax.
Syntax of Lambda Function in python
lambda arguments: expression
Lambda functions can have any number of arguments but only one expression. The expression is evaluated and returned. Lambda functions can be used wherever function objects are required.
Example of Lambda Function in python
Here is an example of lambda function that doubles the input value.
In the above program,
lambda x: x * 2 is the lambda function. Here x is the argument and x * 2 is the expression that gets evaluated and returned.
This function has no name. It returns a function object which is assigned to the identifier
double. We can now call it as a normal function. The statementdouble = lambda x: x * 2
is nearly the same as
def double(x):
return x * 2
Use of Lambda Function in python
We use lambda functions when we require a nameless function for a short period of time.
In Python, we generally use it as an argument to a higher-order function (a function that takes in other functions as arguments(). Lambda functions are used along with built-in functions like
filter(), map() etc.Example use with filter()
The
filter() function in Python takes in a function and a list as arguments.
The function is called with all the items in the list and a new list is returned which contains items for which the function evaluats to
True.
Here is an example use of
filter() function to filter out only even numbers from a list.
Example use with map()
The
map() function in Python takes in a function and a list.
The function is called with all the items in the list and a new list is returned which contains items returned by that function for each item.
Here is an example use of
map() function to double all the items in a list.
Check out these example to learn more:
Thank you :)
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