Lambda is another way to define a user define function.It is also called anonymous function which accepts any number of arguments or parameters but returns single object.
Anonymous/Lambda functions are defined using the lambda keyword.
lambda arguments : expression
>>> # lambda a,b : a+b >>> #to call, to give it a name >>> add=lambda a,b:a+b >>> add(10,20) 30 >>>
Lambda function has no name. It returns a function object which is assigned to the identifier add. Then we can call it as a normal function.
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.
The filter() function 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 only those values corresponding which function evaluates to True.
Below are the execution steps which are performed with filter() function
Step 1 – Fetch each and every value in iterable Step 2- Apply the function Step 3 – Return Original value for which function is True
>>> list1=list(range(1,10)) >>> list1 [1, 2, 3, 4, 5, 6, 7, 8, 9] >>> new_list=list(filter(lambda x:x%2==0,list1)) >>> new_list [2, 4, 6, 8] >>>
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.
Below are the execution steps which are performed with filter() function :
Step 1 – Fetch each and every value in iterable Step 2- Apply the function Step 3 – Return evaluated value from function
>>> list1=[x for x in range(1,10)] >>> list1 [1, 2, 3, 4, 5, 6, 7, 8, 9] >>> new_list=list(map(lambda x:(x*2),list1)) >>> new_list [2, 4, 6, 8, 10, 12, 14, 16, 18] >>>
Ashwini Verma on Apr 17, 2020 at 12:04 am
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