#43 Python Tutorial for Beginners | Filter Map Reduce
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In this lecture we will learn:
Filter Map and Reduce in Python
Use of filter(), map() and reduce() functions
How lambda function can be used with filter map and reduce
Syntax of Filter, Map and reduce function
Difference between filter(), map() and reduce() functions
#1
Lambda function can be used with these three functions:
1. filter()
2. map()
3. reduce()
#2
filter() function will take a list and do filtering and give values.
filter() takes a sequence and also returns a sequence.
filter() function takes two arguments: function and iterable.
filter(func, iterable)
We have to give the definition of a function that we have passed as a condition in an argument.
The defined function should return a value of either True or False based on the condition.
Then, filter() will take the value that is returned by the defined function and does perform filtering based on this value.
In the defined function, we need only two things i.e, a variable and an expression. So, we can also use the lambda function instead of using the normal function to define the condition for a filter.
-Lambda reduces the number of lines of code and makes it more precise.
Filter() simply returns the iterable passed to it.
#3
map() function is used when we want to change the value of every element of a list.
map() function also takes two arguments i.e., a function and an iterable.
map(func, *iterables)
To get the result as a list, the built-in list() function can be called on the map object.
We have to define a function that we have passed as a condition in an argument.
The defined function should return any value.
The lambda function can also be used in an argument as a function instead of defining the normal function for the logic.
map() function returns a list. The function returns a map object which is a generator object.
#4
reduce() function is used to reduce the number of values from a list.
reduce() function belongs to a module known as functools.
We have to import the module functools from the library to use the reduce function.
reduce() also take two arguments i.e., a function and a sequence.
reduce(func, iterable[, initial])
We have to give the definition of a function that we have passed as a condition in an argument.
The lambda function can also be used in an argument as a function instead of defining the normal function for the logic.
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Know what is the difference between filter, reduce and map:
map: Takes a function f, and a list L1, and returns a list L2 obtained by applying f to every element of L1. Say f is a function that takes x and returns 2x. Then, map(f, [1,2,3,4]) returns [2,4,6,8].
reduce: Takes a binary operator f, a list L and a seed value (or identity element). It returns the seed value if the list is empty. Otherwise, it applies the binary operator f to the seed and first element of L, then applies f to the result of this and the 2nd element of L, and so on till L is exhausted. The result is returned. This can be seen as a generalization of factorial function.
filter: Takes a boolean function f and a list L1. It applies the function to each element of L1, and list of those elements that give true is returned.
#insmot
Awesome
map function always returns an object.
One need to convert to list explicitly.
Thanks brother
didn't get about reduce function
Perfect
Finally found a cool programmeer who teaches these concepts in best possible way❤❤😇 Thanks navin sir
Sir, you have made boring topics interesting for us..i love your teaching method..Great job!!
this is one of the best python tutorial series for begineers
and the main part is it is free thank you sir
oh god! you are simply answering all the questions that pop my head. thank you navin. you have no idea what a great part you are holding in my life. because of you, im fearless and ready to learn programming. thank you for saving my life.
finally found a good tutor who does'nt just dump all the codes and and leave logic behind completely making it boring and useless to watch.
really amazing sir.
the form of steps u choose while teaching is unique and more understandable as compared to other lecturers thank u sir great explanation☺️
In case anyone need more information about the difference between filter, map and reduce:
Difference 1:
1. 'Map' takes all objects in a list and allows you to apply a function to it. The result is usually the same quantity of items as in the main list but with some execution(as specified in the function).
2. 'Filter' takes all objects in a list and runs that through a function to create a new list with all objects that return True in that function. Not necessary that it will output same number of items as present in the main list.
Difference 2:
1. In Map you can use multiple iterables definition : map(function_object, iterable1, iterable2,...)
2. Whereas in filter only one iterable can be used definition : filter(function_object, iterable)
Difference 3:
Further in filter the function_object has to return boolean only.
Hope it helps! :) #insmot
thanks a lot
Hey, Thanks for this clarification. but, you didn't mention the purpose of reduce function there :)
It's helpful
"that's what programmers do, making things cool" and how cool he looks with that action ;)
makkhan lagana band karo rre xD
@@harshwardhansingh617 lol
tum toh bare heavy driver ho
Seriously your Python videos are amazing.
kudos to you
such a headache of lambda syntax clarified so simply. Thankx.
You are a teacher of note ... not only a coder ... Thanks for the effort. If I can do anything to help you expand ( other than liking or subscribing ), let me know.
Legend says, the hardest part of programming is naming the variables.
Lambda is my new crush ,😍😍❤️❤️
I love lambda
Indeed!
really pandey g,....i am also pandey............are u student??
Than you sir, after working out this problem myself in laptop, this become simple now... You are a greater teacher and thanks for making me to sit here till above 40 video series. Everyday waking up with your videos make my day very active.... Thank you!
i was married to java and its version 8 features; after watching this i am planning to cheat in my relationship
you will be presented in the court if you do this :)
I will stay faithful to both
Ill treat java as a friend (friendzoned)
😝
😃
Java will divorce you
from functools import *
num = [2,4,5,6,7,8,9,1,0]
odds =(list(filter(lambda n: n%2!=0 ,num)))
square=(list(map(lambda a: a*a,odds)))
sum=(reduce(lambda x,y: x+y,square))
print(sum)
I like the way you teach us, Navin. I am learning a lot from your videos.
From this video, I learned how to find Factorials of a number with just two lines of code using reduce.
from functools import reduce
print(reduce(lambda a, b: a * b, range(1, int(input("Enter a number: ")) + 1)))
cool bro, really appreciate your help on learning python :)
Factorial!!!
Hello Sir,
Thanks so much for the lessons. I have coded factorial of a number using reduce functions. Its working:-)
from functools import reduce
s=[]
n=int(input("Enter the number"))
for i in range(n+1):
if i==0:
continue
else:
s.append(i)
print(s)
total = reduce(lambda a,b: a*b,s)
print(total)
Many many thanks Navin for clearing the concept of Map Reduce. You are a gem. Super likes
Your smart explanation helps me to get out of my fear in learning python😍😍😍
"that's what programmers do, making things cool" ; thank you a lot Navin Sir
This is so amazing! I learnt a whole lot about not just lambda from this video, but also these three other useful (albeit advances) functions! Thank you so much!
So enjoyable your teaching skill. Really i am getting all this things free. Thanks sir great heads off.
Class Moniter could you please let me know whether this channel has videos on python and are they easy to understand? Thanks in advance.
"Hats off" is the expression
@@MegaCherry0 This is a reply after 7 months but I can confidently say that this is the best channel for python. I regret not discovering this channel earlier
SaFFire thank you so much buddy.
@@MegaCherry0 you're welcome. I'm 7 months late though 😅
Sir...your teachings are awesome and you are a blessing to a lot of new programmers
I have watched so many tutorials and had no idea until i watch this masterpiece🎉
Thank you! Wishing you all the best 🙏🏼
After a long time, I finally understood the concept of Lambda, Reduce, Map function. Great video and well explained. Thank you so much sir. Now eager to learn more and more every day through your videos. Thank you so much, keep up the great work.
Navin sir can u make more videos and more concepts as soon as possible because we are understand very easy with ur explaination
NOTE : TRY TO MAKE SOME PROJECTS AND SOFTWARE USING THIS CONCEPTS
demanding huh.....
Very helpful to me. It's crystal clear. Prior to watching this video I could not understand filter and map.
You are the best.... no teacher ca teach like you
Comparaing it with java in java we have to use -> operator here only : and also here we have to write lambda
You are really a fabulous teacher
🤩🤩🤩
Love how you kept in your mistakes. Very honest.
After watching this video my all doubt got clear hats off to sir quality and method of teaching lit.. Tx
This is the Beauty of python.... And sir hats off for ur teaching
I saw you video after 2 months and editing level is whole different level. I got so much inspiration from you. thank you sir for making this video!!
I thought your vids were useless at the first
but then I understood that your vids r very helpful
thank you soo much.
Navin you are a great teacher!
4:03 best part of the Video
thank me later
😂😂😂😂🤣🤣🤣
🤣🤣
That scene was really funny
The way he said
😂
Navin sir you are a legend 🙏🏻❣️
Thanks again
1:05 , chris Evans should listen this😂😂. #CaptainAmarica
you are awesome teacher ever ... And your teaching style is really energetic
This man is an absolute legend
sir , U r my hero shall i tell in my mother toungue,
Marana mass
Sorry to ask. Which language.?
@@allofmystuffs tamil
Thalaivar 🔥
I have made a use of lambda and map() method and would like to share ..
And here is the snippet :
a,b=[int(x) for x in input("Enter two values seperated with spaces : ").split()]
tup=( lambda c,d : c+d, lambda c,d : c-d , lambda c,d : c*d , (lambda c,d : (c+d)/2))
dic=dict(zip(('Sum' , 'Difference' , 'Product' , 'Average'),map(lambda x : x(a,b),tup)))
for j in dic:
print("{} : {}".format(j,dic[j]))
Hope this gets useful in some way.
Thank You :)
Your explanation is very awesome. Thanks a lot!!
Your teaching technique is so lovely!!!
simple and clean Explanation
thank you sir
this was the only tutorial I undestood about map filter an reduce
u makes the concept understandable
Great tutorial and by the way THANKYOU for making these videos AD FREE.
it's brief and clear .Thank you so much sir
he said that these functions are not easy, but I found them so easy : P
navin sir i am very happy for your lectures, its very clear cut and good ...a request form my side to plan videos on problem solving python, which is used for placements for some lakhs of engineering students...i am expecting that one.
The next level of awesome teaching
Sir please start with python on these weekend it will help those people who are watching your python playlist
i knew lamda function but filter ,map and reduce is useful for handling huge data ... so thanks for video
Find average of list:
from functools import reduce
list = [1,2,3,4,5,6,7,8]
ave = reduce(lambda a,b: a+b,list)/len(list)
print(ave)
you are helping many people sir. keep going
it's 2024 still we are following your videos even though its 5 years ago B'coz of your excellent explanation and amazing programming
from functools import reduce
nums = [1,2,3,4]
odds = list(filter(lambda n:n%2==1,nums))
print(odds)
x = list(map(lambda n:5*n, odds))
print(x)
y = reduce(lambda a,b:a+b,x)
print(y)
Output
[1,3]
[5,15]
20
from functools import reduce
lst = [2,4,5,25,21,66]
evens = list(filter(lambda n : n%2==0,lst))
doubles = list(map(lambda n : n*2,evens))
sum = (reduce(lambda a,b : a+b,doubles))
print(evens)
print(doubles)
print(sum)
Very important video but please sir try to upload more videos daily. After uploading complete series please sir make some projects/softwares.. it will be very helpful to understand the real world problems 🙏🙏🙏..
Sir your class is fantastic, more understandable
Navin sir thank you soo much for this series...I learned alot from this series...it is very easy and helpful..thank you soo much for your efforts ☺️☺️
Big Data concept is so relatable for me to understand this concept.❤❤
I like the way of u teaching sir superb...... 👌👌
Hands down the best place to learn Python❤❤❤❤❤❤
Thank you very much. You are a genius.
Thank you so much the only tutorial that i can actually understand!! ♥♥
Sir, all lambda functions are working similar(filter(),map(),reduce()).
Then what is the main difference between them.
Among three which function is better to use.
loved the method of your explaining
code -->
from functools import reduce
def adding(a,b):
return a+b
def update(n):
return n*2
num=[1,2,3,4,5,6,7,8,9,10]
even=list(filter(lambda x:x%2==0,num))
print(f"even numbers are {even}")
double=list(map(lambda x:x*2,even))
print(f"double of all the even numbers {double}")
sum=reduce(lambda x,y:x+y,double)
sum=str(sum).center(10)
print(f"the addition of all the numbers ae present in the double are {sum}")
perfectly explained thanks,,,was confused earlier
Excellent explanation !!!
numbs =[]
n = int(input("Enter the number of elements you want to enter: "))
for i in range(n):
a = int(input("Enter the value:"))
numbs.append(a)
evens = list(filter(lambda a : a%2==0,numbs))
print(evens)
from functools import *
numbs = []
n=int(input("Enter the number of value to be added:"))
for i in range(n):
a = int(input("Enter the value: ",))
numbs.append(a)
result = reduce(lambda a,b : a+b, numbs)
print(numbs)
print(result)
Sir all I can say is your perfect..
nums =[1,2,3,4,5,6,7]
evens = list(map(lambda n: n % 2 == 0,nums))
print(evens)
if the function is a condition then it will give true or false according to the input
output : [False, True, False, True, False, True, False]
if we use for loop to seperate evens than it will take time complexcity o(n)..by using lambda what is the time complexicity
Really awesome explanation about this topic, I really love it and understood very well by ur way of teaching...🙏❤️
Sir, Can you please start Machine learning with Python tutorial.
Sir this is very necessary
LAMBDA 4:03 LMAO
Thank you for the tutorial!
great presentation skills sir
all things are clear but i really like comprehensions
The main challenge is when you are done studying and practising this and you continue with the course, someone forgets. and the query here Mr Navin is how can we interact often with these practices like say in some projects so that one knows why we are doing this, this can sink the point once.
f=lambda a: a%2 ==0
>>> nums=[1,2,3,4,5,6,8]
>>> evens=list(filter(f,nums))
>>> print(evens)
[2, 4, 6, 8]
using lambda function..
Good work bro!
list = []
n = int(input("Enter the number of elements you want to enter: "))
for i in range(n):
a = int(input("Enter the value:"))
list.append(a)
if a % 2 == 0:
print("It is an even number : ", a)
else:
print("it is an odd number")
print(list)
' ' ' He is Literally Great ' ' '
from functools import *
lst=[1,2,3,4,5,6,7,8,9]
even=list(filter(lambda n : n%2!=0,lst))
double=list(map(lambda i : i*2,even))
add=reduce(lambda a,b : a+b,double)
print(even)
print(double)
print(add)
Sir, How can you describe so easily and understandably. Hats off Sir
Excellent teaching. Thank you.
You can see mine too. Hope the Python playlist, step by step sequentially arranged by sections, will be valuable. Source files can be found in the description of the each video. There is another playlist , R beginning course in the channel too.
Superb explanation bro😊
Very Nice explanation , Thank you
Awesome work sir and please make more videos like these and give us some projects and assignment 👍🏻💯
wowww!! beautifully explained!!
Super explanation sir
Great Playlist for Python. I like it.
One doubt here, how a+b added all variables without using any loop?
if we have the list abc = [1,2,3,4]
it will take the first two elements from the list and perform the function, the new list now becomes [3,3,4]
the process is repeated till we have a single value
@@mohitsharma4667 for e.g , l = [2, 4, 6, 8]
>>> reduce(add_all, l)
2 + 4 --> 6
6(2 + 4) + 6 --> 12
12(6 + 6) + 8 --> 20
final sum: 20
that's how reduce() works! :)