Lambda Functions in Python: trickcode

What is Lambda?

Lambda function used  to  create a  small  anonymous function without name. Lambda is a powerful python function with some limited capabilities. Lambda function is also referred to as an anonymous function . Lambda function can accept any number of elements as input but only one expression is evaluated and returned.

Why  Use Lambda Function?

Lambda Function is anonymous. Anonymous means  we  don't  need  to  give  a name to  lambda  function when   we  are  writing  single-line  function  prefer  lambda function instead of using normal functions.  To write a normal  function we need  a def keyword  to  define  a function and  return  keyword  is used to return something from  a function. Lambda function requires a lambda keyword to define a lambda function and don’t need  any keyword for return values from lambda functions.

Syntax

Python lambda single lines

Python lambda single lines

 Example

                          lambda a: a+10

The above function accepts 1 variable and returns it after adding 10 into it.

Example Of Addition of Two-Variable

                                                              lambda a,b : a+b

Above function accepts 2 variables a and b and return addition of a and b.

Example Single Inputs

 Using Lambda Function

The output of the Above Both Programs

Example Multiple Inputs

Using Normal Function

Using Lambda Function

The output of the Above Both Programs

Lambda Function can be used with the Following python built-in functions

●  map

●  filter

●  Reduce

Note : Lambda Function has some limited capabilities such as only one expression can be evaluated.

What is a Map?

map()  is a   python  a built-in function used to apply a specific function on every element of an iterable object such as list, tuple, strings, etc . map() returns a  mapped object after applying a function to every element from an iterable object.  map()   can be used with a  normal function or lambda function.

Syntax

                           map(func, *iterables)

Where

func: a normal function or a Lambda function. Iterbales: Any iterable Object such as list, string, tuple, etc..

Examples

We are going to practice here multiple Examples using map() function with the help of normal user-defined function and a lambda function.

Add 5 To every list Element (normal function)

Add 5 To every list Element (lambda function)

The output of the above Examples

Result of Mapped Function :<map object at 0x7ffaeb8714a8> 

Original List : [1, 2, 3, 4]

After Applying Map Function(Add) : [6, 7, 8, 9]

Convert a String Numbers List to int Numbers

Output

                          

Original List (Datatype)

                            type(lst[0])   :    <class 'str'>

Converted List (Datatype)

                     type(final_result[0])    :    <class 'int'> 

Addition of Two numbers List

Output

Addition of list1 and list2

list1	1	2	3	4
list2	5	6	7	8
Addition	6	8	10	12

Reduce

Reduce() function is not a  part  of python built-in function you need  to import  it from functools. In python  3 most of the developers ignore the use of reducing () method.  reduce() is  a  function  used   to  reduces a  iterable object to a single value by combining element via a supplied function.

Syntax

             from functools import reduce 

                           reduce(function, sequence[, initial])

Where

function  : Any lambda or normal  user-defined function. Sequence : any sequence iterable list

Example

Consider

Lst1 = [1,2,3,4,5] Output Should be

15

Reduce Calculate the Sequence if  reduce(lambda a,b :a+b,Lst1)

Res = ((((1+2)+3)+4)+5) Res= 15

Example

# Import reduce from functools from functools import reduce

Lst1 = [1,2,3,4,5]

result = reduce(lambda a,b :a+b,Lst1)

print(f"Addition of All Elements in Lst1 is : {result}")

Output

Addition of All Elements in Lst1 is: 15 

Exercise

1.  Write a Program using lambda to calculate the square of a given user input radius.

2.  Write a Program using lambda to multiply three  elements

3.  Write a Program For Addition of Following Lists

              Lst1 = [0,1,2]

              Lst2 = ["3","4","5"]

4.  Write a Program to find out numbers from range(1,121) divisible by 3

5.  Write a Program to  calculate the sum of odd numbers (1,100)

See Also :- What is Firebase? , SQL vs NoSQL or MySQL vs MongoDB,Best R vs Python for data science and Analysis