Python: RECURSION Explained 

To understand recursion, you need to first understand recursion.

Thank you for this. Its harder than you would think to find a beginner recursion tutorial thats easy to understand

Again, another video that sums up 3 hours of lecture into a video under 10 minutes.

This video is definitely one of the most comprehensive explanations of recursion for beginners. I always wondered how calculations were being done if the function is repeatedly calling itself but as explained in this video the function keeps calling itself until it reaches the base case and then only are the calculations done. I love the analogy of digging a hole.

At 4:00 you explain recursion better than the ton of videos i've been watching. thanks

Was puzzled by recursion until you explained that it digs down to the base case and then works back up. Thank you

Thank you Joe! Now I have a basic understanding of RECURSION and can see how searches such as tree traversals and binary code work. :)

I get it. I GET IT.

Sir your are doing great job.It's very helpful when you first give the pseducode of that algorithms then give the programs in specific language implementation..love you sir.please give more and algorithms implementation in java and python programming languages..this will be very helpful for us...

I needed to refresh my memory on recession and your video was short and straight the point, THANKS

Amazing video, not monotonous, but still gives a good overview and lesson on recursion in python! Keep up the good work!

Best explanation of recursion I have come across on the net.

Clearly spoken, good explanation, fairly easy to understand. Well done.

this video gives it to you well, no beating around the bush to lengthen the viewing time. well done!

Thank you for this explanation, I like that you compared it as "we are digging ourselves deeper into a hole and then digging ourselves out of it"

great job! keep it up! finally, a detailed explanation of recursion explaining about the things that going around in the background...

Greatly appreciated for your time to explain these concepts.

Thank you Sir. Blessings be upon you. God bless you with peace.

THANK YOU! BEST VIDEO ON RECURSION!

2019 and I appreciated the visual explanation very much! Thank you.

THANK YOU, DANKE, MERCI, SHUKRAN, SEPAS

Well done! Thank you. Very clear and easy to follow.

I promise you i love you omds this made everything so clear.

Thanks for the explanation. I really appreciate how you explained the part about the memory. This cleared up my confusion. This was organized really well!

Excellent job. Your explanation is clear and easy to follow. Please do more videos like these. Many thanks for your help and hard work.

Thankyou sir for making this kind of helpful video for us. It really helped me to understand what recursion is.

Thank you for actually saying iterative is a loop. Book after book and video after video never say iterative is loop.

Perfectly explained. Thank you

Great video! We are learning recursion right now

That was immensely helpful, thank you!

You explained this amazingly

Simple and to the point.

Great explanation in a simple way. Thanks

Definitely earned a subscribe here, thank you very much Joe

Thank you so much for this wonderful tutorial.

Thank you for the video. I am gratuful for your time and contribution. Kind regards, Akira.

Now I get it!! Thank you very much.

Thanks for explaining this in a such simple and doable manner! 🎉🎉

very well explained, thanks a lot for the illustration !

helpful and to the point, thanks a bunch!

finally understand it now. thank you.

Beautiful. Thank you sir.

Well explained. Thumbs up!

thank you so much, you probably will never see this comment or care but i personally wanted too thank you for helping me to understand recursion better, my computer science teacher was explaining it and I had a hard time understanding but when you explained simpler it it was much easier to understand :)

Thank you man, this was an excellent explanation.

thank you man, very helpful

Very well explained ! Thank you Sir!

thanks bro this helped alot fr. subscribed!!

Great job! Thank you!

Thank you sir, wonderful explanation.

Very easy to understand. Thank you!

Thank god for this video

Rly helpful. Thank you!

A very concise explanation without your face as the focus but rather the issue at hand. The tutorial is on point without having to learn the creation of the universe, which is so annoying. My first Python subscription and like (whoa!).

this was a super good video. i appreciate it. subbed.

wow. Thanks a lot man ❤️❤️

now I get it. thanks!

Thank you, helped a lot.

Great video!

Great video man

thanks for the video!

Very nice! Visualizing it like you did at 4:52 made it extremely obvious and clear. Very good tutorial and explanation.

Great video, btw you don't really need the "else" on 05:10, because if it's not lower than 2 it doesn't go in anyway so you can just write on the same tab as the if "return ...". Thanks for sharing the video! :)

Thank you !

Excellent.

Thanks for this.

Thanks Joe

Watched 20 videos today and I am still dumb as a rock about recursions. I'm ready to pick up knitting or another hobby that doesn't make me question my sanity. Can't keep putting time and effort into computing concepts designed to kick my ass.

Thank you very much!!!

thanks Joe

thanks Joe James

Superb Explanation. Hats-off.

I think I fell in love with the word factorial

Thank you ❤

It would be interesting if you used timeit on both algorithms and see which is faster in python.

before this recursion seemed impossible to me, thanks

very nice video

amazing

Thank you!!!

Thank you

I wont lie, recursion wore me out, but I get it now. Often I like to loop through a directory in python with the os.listdir() function. I realize a for loop will only go through the directory but not directories within the directory.

Thanks.

Came up with a short recursive python snippet while you were beginning to explain the topic. 5 lines, if anyone has a shorter one, post it below ;) def factorial(n): if n > 1: return n * factorial(n - 1) return n print(factorial(5))

Thanks🖤

thank you

Lovely Vid :)

Hey Joe -- Really luv your videos -- can you pls do a video tho with the list what one needs to learn to become really more-or-less professional developer? I.e. Like im personally trying to learn it by myself and think that sorta Im on early-intermediate level of proficiency; however, there is not even one single good source that Ive encountered that would really expand more on actual Software Engineering/Computer Science *list of topics one need to know* rather than just Foundations/Syntax. I.e. what CS areas one MUST know like, for instance, this concept of recursion: Like the following is the list that came to my mind but perhaps you can add on from your experience: 1. recursion 2. CRUD 3. algorithms 4. MVC/MVT for Django 5. What are design patterns and why one needs to learn them 6. version control 7. Waterfall engineering model 8. Types of programming: functional, OOP, etc -- why need different? 9. Dynamic programming vs. static 10. What/Why testing is needed? 11. SCRUM/Agile etc 12. how to better learn problem solving skills for coding/approaches/methods of thinking etc, other important topics/concepts/areas .... and etc and in all fairness, someone who would do, say, 1hr/30 mins lecture with literally covering all these topics for like 30sec/1 min each per term in 1-2hr would be an absolute GOD of youtube!!!! for all software developers as he would provide a sorta oxygen to combine all CS concepts (not just syntax) into one sorta coherent and comprehensive fashion. Even just mentioning all the terms, saying, ok -- CRUD is for websites, Waterfall model is just for writing your code, OOP is for writing logical steps for organizing processes and attributes of objects etc Thus, the biggest problem for the inexperienced like me is that all these terms come just from trial and error of exploring and working on problems rather than anyone really covering them first and sorta providing a blueprint or a path on how to become an advanced software engineer I hope I explained what Im looking for but if not, please revert and I will be happy to expand. and Many thanks for your channel again!

Thanks a lot

factorial = lambda n: reduce(lambda x,y: x*y, range(1, n+1))

MY BRAIN HURTS

thank you for this video, super helpful! i need help understanding the iterative function at 8:10, esp the fact*=i part....could someone please help me?

thanks

Great tutorial. On this topic I face a bottleneck and not able to explain. I tried to sum all natural numbers of 'n' and not able explain the mechanics. def sum_n(n): if n== 0: return 0 else: print('n ', n) res = n + sum_n(n-1) print('res ',res) return res print(sum_n(5)) n 5 n 4 n 3 n 2 n 1 res 1 res 3 res 6 res 10 res 15 15 As the loop run, n is reduced to 1... it is clear. However, res adds cumulatively AFTER this. I expected print(res) to print one value (15). Is there a loop between 'res = n + sum_n(n-1)' and 'return res'?? It is slightly different to your example. But can you clarify?

Thank you. I get it ,plz can you make a video on tables ?

I think new people need to understand the call stack before they get recursive functions. You can get the structure of recursion in the abstract well enough, but not understand how it seems to magically spit out the answer when it stops recursing.

I have a recursive function written that wants to “unwind” itself after the base call has been executed. How do stop/prevent unwinding

Wow I'm such a dummy. I didn't realize the difference between factorial and factor until now lol

Excellent video. In recursion how is the fact tracking the total. I see in code how we are tracking the total using iteration, but how does it remember the total using recursion? Hope my question makes sense.

Could someone explain on a lower level how recursion works? How does the interpreter assign each recursive call to memory? how does it keep track of the call stack?

Is it normal that my for loop can compute much larger factorial numbers than the simple recursion my prof codded?