Advance Python map function, Lambda Function, Python map Filter with Example.

It is a powerful python ready-made function to perform implementation in various ways with List, Dictionaries, tuples, Sets, and also with many mathem

Python Lamda Function:  

Lamda Function is an Anonymous function that is directly called without creating any object and reference. It is a powerful python ready-made function to perform implementation in various ways with List, Dictionaries, tuples, Sets, and also with many mathematical operations. Like all functions define with def keyword in python but in case of Anonymous function it doest start ith prefix def keyword and directly declared and initilise by lamda keyword with N type of argument.  An example is given below.

Syntax:

lambda arguments: expression

Normal Function Lamda Function

def square_root(n):
    return n*n
print(square_root(12))
#output: 144
square_root=lambda x: x ** 2
print(square_root(12))
#output: 144

my_list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
a=[]
for i in my_list:
    if i%2!=0:
        a.append(i)
print(a)
#output: [1, 3, 5, 7, 9]
my_list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
filtered = filter(lambda x: x % 2 != 0, my_list)
#output: [1, 3, 5, 7, 9]

List_A = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
List_B,List_C=[],[]
for i in List:
    if i%2==0:
        List_B.append(i)
    else:
        List_C.append(i)
List_B.extend(List_C)
print(List_B)
# output: [0, 2, 4, 6, 8, 1, 3, 5, 7, 9]

List = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
result= sorted(List, key = lambda x: x%2)
print(result)
# output: [0, 2, 4, 6, 8, 1, 3, 5, 7, 9]

def math(x,y,z):
    if z==0:
        return x+y
    else :
        return (x+y+z)/3
print(math(2,4,6))
#Output = 10 or 6.0

x = lambda a, b, c : a + b if c==0 else (a+b+c)/3
print(x(5,3,10))
#Output = 10 or 6.0


 

Python Map Function: 

Python Map Functions are more usable with the Lamda function. Lambda function can iterate only one object at a single time and can't iterate with many objects at the same time. Python Map Function overcome this Python Lamda function limitations. Python Map functions are able to itrerate or compare two sets of objects simultaneously.
Example: Suppose multiply the two Numbers List with each other ( List1=[2,3,4] & List2=[5,6,7] ). So the Lambda function can do this with the help of the Python Map Function. An example is given below.



Python map lambda function:

Map function can implement in various way. Using with Lamda is a one of them.


Map vs Dictionary in python :


MAPDictionary
The map is a function in python used to perform various operations and able iterate over objects list. Dictionary is an important part of python data structure that stores data in {Key: Value} format. Map functions are used in dictionaries to perform critical tasks easily.
The map function can't be used as a data type in python It applies a function to a series of values and returns the result as a list or object. Dictionary is also a Map but usually it has order of enumeration specified so its method calls the callback function in order of key/value
Syntex: map(function, iterable, ...)Syntax: dict_A= { "key":  "values"}
Apply function to every item of iterable and return a list of the results. And If you don't wrap it in a list in Python 3, you will get a map object:Dictionary is the name of a native map container. For example, dictionary in Python or Javascript. Usually is a hash or a red black (self balanced) binary search tree.
A map is a function that maps a function to an sequence. Map is just, as the name points out, a bijection between two sets: keys and data. So the data is ‘mapped’ with keys.A dict() can be called an associative array. Ordinary arrays, typified by sequences, use a numeric index, but a dict's index is made up of the key objects.
Map iterate in each indexes of dictionary but cannot edit it diretly.A Python dict is dynamic, allowing us to add field names at run-time through calling python pre-build methods.

Python map example:

>>>Temp_list = [2,3,4,5]
>>>Output = list(map(lambda x: x**2, Temp_list))
>>>print(Output)
[4, 9, 16, 25]



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https://www.freecodecamp.org/news/lambda-function-in-python-example-syntax/
https://www.geeksforgeeks.org/overuse-of-lambda-expressions-in-python/
https://webkul.com/blog/advanced-python-features-lambda-map-filter/#:~:text=Lambda%20function%20has%20one%20expression%20and%20can%20take%20any%20type%20of%20argument.&text=Map%3A%20Map%20is%20a%20Python,like%20a%20list%20or%20dictionary.
https://www.digitalocean.com/community/tutorials/how-to-use-the-python-map-function
https://www.guru99.com/python-map-function.html

About the author

D Shwari
I'm a professor at National University's Department of Computer Science. My main streams are data science and data analysis. Project management for many computer science-related sectors. Next working project on Al with deep Learning.....

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