10 Python Comprehensions You SHOULD Be Using

Рет қаралды 81,591

Күн бұрын

In this video, I will be showing you 10 Python comprehensions you can & should be using. These comprehensions will progress in difficulty, so be sure to stick around until the end of the video!
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🎞 Video Resources 🎞
⏳ Timestamps ⏳
00:00 | Overview
00:11 | Basic List Comprehensions
02:06 | Comprehension Condition
04:22 | If You're Serious About Becoming A Developer
05:20 | Comprehension With Multiple Conditions
07:42 | Multiple List Comprehension
09:18 | If/Else In A Comprehension
11:22 | Nested List Comprehension
14:32 | Transformation In Comprehension
15:38 | Dictionary Comprehension
16:47 | Set Comprehension
17:49 | Generator Comprehension
Hashtags
#techwithtim
#programming
#python

Пікірлер: 110

@TechWithTim Ай бұрын

If you like this style of teaching check out my full software development program: techwithtim.net/dev

@DarinCox-or1iq Ай бұрын

Job opportunity 🙌 🙏 is the money you have given to many of these people and I will send them some more important information about what you have done ✔️

@satheshasachithra Ай бұрын

could you do javascript beginner to pro challenges on code wars or anyotherway

@MiAmigoKier Ай бұрын

May I ask, what is your keyboard, it sounds great btw

@DarinCox-or1iq Ай бұрын

@kerrykreiter445 Ай бұрын

Absolutely the best tutorial I’ve watched on comprehensions. Thank you for making it very understandable. I would also appreciate the same type of video covering Lambda functions. Thanks again for helping so many!!

@mikec64 Ай бұрын

I found the way you formatted the comprehension that calculates squares is a really helpful way to think about comprehensions, even if I compress them to a single line. In that form, it looks like the comprehension just skips the result=[ ] statement, which I always thought was ugly. And in nested loops it gets rid of all those intermediate lists and variables. For the first time they look more elegant to me.

@lucasseagull8282 Ай бұрын

Man, you grew a lot in past 3 years :)) I'm just watching your video called: Python Selenium Tutorial #2 - Locating Elements From HTML, where you are referring to your website for testing. However, it's no use as the website is now different - can you do the remake of your selenium tutorials / make it up-to date? Thank you and good luck!

@user-ty1gv6xg1o 14 күн бұрын

Man... I love how clean this looks

@eladiomendez8226 Ай бұрын

Is this list comprehensive of all comprehensions ? 😅

@gaussdog 27 күн бұрын

Is your comprehension comprehensive?

@YarPirates-vy7iv 17 күн бұрын

As a connoisseur of dad jokes I want to thank you for this contribution. 🎉

@NearLWatson 5 күн бұрын

Comprehensive list of comprehensions to help comprehend a list of comprehensions within which the list comprehension is included.

@Soyosan22 Ай бұрын

This is an absolutely excellent video. Your examples and explanations are always great. I think it is time for you to start working on a Python book. I am sure it will be a huge success. :)

@kapibara2440 26 күн бұрын

Great content, like always from you. Thanks Tim! Greetings from Poland 😊

@swagatopablo 26 күн бұрын

Most comprehensions can be replaced by some combination of map and filter, which I find far cleaner. Further, in most cases, you will iterate through the iterator only once, in which case, you can leave it as an iterator (map and filter) form until you use it (unlike, for example, using comprehension to give you an iterable). This is far more pythonic and memory efficient too.

@elatedbento 19 күн бұрын

Things are a bit gray here. You can easily replace the list comprehension to a generator comprehension by just changing to parenthesis, in case you need that memory efficiency. Most developers nowadays advocate for list/gen comprehensions over map and filter statements, for readability and performance. There is nothing wrong with map and filter, though.

@swagatopablo 18 күн бұрын

@@elatedbento Curious, do most developers advocate against map and filter? Why? I am just curious if there have been some benchmarking on performance or some other motivation behind it that I don't know of. In general, I love the clarity of functional constructs which explains my bias.

@sdmagic Ай бұрын

Very well done. Thanks!

@Ohiostategenerationx Ай бұрын

Looks good. I'm just now learning it but as far as I can tell it looks way better than the original code.

@i5presnt562 22 күн бұрын

I needed this kind of videos thx so much

@ricdelmar4961 Ай бұрын

Another interesting point about generator expressions, is how they work with the all and any functions. Those functions will use the same kind of short-circuit evaluation that compound conditionals use -- that is, they will only evaluate as many items from the generator that they need in order to determine whether the result should be True or False.

@BruceDuncan 25 күн бұрын

Oof you got me. Been writing python for 15 years and never knew that you could have multiple `if` statements in a comprehension. I have always written `and` and assumed you made a syntax error 😂

@wandksitesupport2777 16 күн бұрын

nah jit bro got a whole level of python knowledge but still dont know that

@nirty6340 14 күн бұрын

@@wandksitesupport2777 it doesnt matter to be honest correct me if i wrong but if you replace all if's with and expect first it would work the same

@AlexTrusk91 Ай бұрын

Thanks, pretty edutaining stuff

@DrDeuteron Ай бұрын

Nested list comp: >>>flattened = list(chain(*matrix)) chain is from itertools.

@jamesarthurkimbell Ай бұрын

They also have a chain_from_iterable for this case... but I agree, I'd rather just type the star

@andresbonelli Ай бұрын

You can even nest comprehensions inside of other functions, inside of user inputs... ie: print(*(list("Hello" for _ in range(int(input("How many 'Hello' would you like to print? ")))))) Python is wild...

@user-ts9ks8in2n Ай бұрын

Comprendre! Thanks Tim.

@shapunna6151 7 күн бұрын

Thanks a lot ❤

@krzysiekkrzysiek9059 25 күн бұрын

And these are the best kind of tips 👌

@yasufadhili Ай бұрын

Thanks alot again

@Indently Ай бұрын

07:28 I actually never knew you could insert multiple conditions like that, pretty cool!

@BrianStDenis-pj1tq Ай бұрын

Great video. One thing you might add is a speed comparison. I believe comprehensions are extremely fast, and while one might argue readability, performance is far superior.

@GigasAhriman Ай бұрын

I've always wondered about speed comparison but I have no idea how to set that one up

@BrianStDenis-pj1tq Ай бұрын

@@GigasAhriman The last example in this video showed a scenario. Star with a range of like 100M. Then make a list of the integers. Do it in a for loop (with list.append()) and then in a comprehension. Use time.perfcounter() before and after.

@GigasAhriman Ай бұрын

@@BrianStDenis-pj1tq that's the first time I've heard of time.perfcounter() Ty

@BrianStDenis-pj1tq Ай бұрын

@@GigasAhriman BTW, I left out a character, its time.perf_counter()

@mikec64 Ай бұрын

@@BrianStDenis-pj1tq Thanks for the perf_counter tip. I ran the 3D array (1000 x 200 x 500) test both ways. The loop was 4.7 sec, the comprehension was 2.6 sec. Results varied if I used numbers too small or so large that they ate up all my RAM.

@largewallofbeans9812 2 күн бұрын

For number 1, it’s much easier just to write list(range(10)) or [*range(10]. Of course, this doesn’t allow for manipulation of the numbers in the range, but it’s still something to be aware of. Same type of thing goes for the conditional comprehension and the filter function.

@AirLight1646 10 күн бұрын

What a comprehensive guide.

@KeithKazamaFlick Ай бұрын

my guy tim. cheers buddy

@adiaphoros6842 Күн бұрын

The nested list comprehension would be more readable to me if the syntax goes inside out. For example: flattened = [num for num in row in array]

@andiglazkov4915 Ай бұрын

Thanks 😊

@stefanvanbraam4378 21 күн бұрын

Hi. Great video. Do you have a video that teaches you how to change the text color (scope) such as print, for, if statements in Sublime 3? Thanks

@user-qs2hn9zp3d Ай бұрын

tq bro.. I have learned lot. 🥺🥺

@TechWithTim Ай бұрын

Welcome 😊

@Da_phuc Ай бұрын

Ah yeah!! Good stuff aahhhhhhhhh!! More baby boi !!!

@jackiesofir4660 Ай бұрын

This is the only way we populated list where I work. Literly appending is I'll advised

@godwinv4838 Ай бұрын

thank you

@jamesarthurkimbell Ай бұрын

Another benefit is that variables don't leak out the way they do with for loops. Less of an issue if you're using underscores, but still.

@dmaynor 27 күн бұрын

How does the example at &t6:30 work? you don't have to terminate login in []?

@DrDeuteron Ай бұрын

regarding the check on string length (5:40): string[slice(None, 1)] == 'a' and string[slice(None, -2, -1)] == 'y' works so: >>>valid_string = list(filter(lambda string: string[slice(None, 1)] == 'a' and string[slice(None, -2, -1)] == 'y', options)) takes care of business, buy may necessitate a code comment.

@chinzorigyou Ай бұрын

Thanks

@tincustefanlucian7495 20 күн бұрын

nice synthesis. I'm using all of them(except multiple if condition, nice one). I would add another dictionary comprehension that I use often, when i want to filter items or find items in a really big dictionary: hay_dictionary = {"first": 1, "second": 2, "needle":4, "second_needle": 5, "last": 6, .................} a really big dictionary {k:v for k, v in hay_dictionary.items() if "needle" in k} this will return only the item that have in key "needle" {"needle":4, "second_needle": 5}

@YOURMOTIVATOR-km2gy Ай бұрын

Big fan man

@shawn445 Ай бұрын

This is a great video but I've been having the issue of figuring out when I would use these in real life scenarios m it would be great if I had applicable examples

@ToxoYoutube Ай бұрын

Hey tim, i was wondering if you had any videos on your channel that could help me with DSA in python. Do you have like a youtube playlist?

@kazmi401 Ай бұрын

The have a paid course on algoexpert. But that's not for beginners. i have a year of experience. even that's was a little bit hard for me. but now i am smooth. mmmm it was great "i think".

@nascentnaga Ай бұрын

I did not know sum() would store the internal value. That is very interesting.

@mahmoudhasan6954 Ай бұрын

You can apply sum(),max(),min(), len() and other functions as well

@justliberty4072 12 күн бұрын

I'm surprised that Tim didn't mention the time-performance benefits of using comprehensions.

@AnatoliyRU 18 күн бұрын

for first `values = list(range(10))` is better

@elatedbento 19 күн бұрын

Comprehension with multiple conditions

@TragicGFuel 14 күн бұрын

Yeah personally, these comprehensions would confuse the hell out of someone who's unfamiliar and probably would have understood the more verbose syntax easier.

@CynicAtLarge Ай бұрын

3D example would be more clear if you used different range values for each dimension.

@TechWithTim Ай бұрын

Good point that was not the best example

@svdden_strike Ай бұрын

Can you teach us how to create a CMS for a website

@gogasaldadze1639 20 күн бұрын

i would prefer to use this type lis=[i for i in a if i[0]=='a' and i[-1]=='y']

@giovannisins Ай бұрын

Shouldn't at 5:59 the first condition be greater than or equals to 2 like you show after?

@HarnessedGnat 17 күн бұрын

In the first group the unwanted options are being filtered out, (toss out anything too short), and in the comprehension he is selecting for those strings that match the requirements. Same end result but one test is the inverse.

@giovannisins 17 күн бұрын

You are right, thank you

@DrDeuteron Ай бұрын

even/odd. since if is the new goto (harmful), I select with: {0: 'even', 1: 'odd'}[x % 2] which is why devs hate me. Actually, I'd map the list to (2).__rmod__ and map that to dict.getitem.

@ImmacHn 5 күн бұрын

So basically, sintactic sugar for reduce/map , got it.

@erikjohnson9112 25 күн бұрын

I don't get a generator for your last example: >>> sub_of_squares = sum(x**2 for x in range(100)) >>> type(sub_of_squares)

@JanKowalski-dm5vr 24 күн бұрын

This is generator: sub_of_squares = (x**2 for x in range(100)) and you can use next(sub_of_squares) And this is sum function that call generator instead create whole list sub_of_squares = sum(x**2 for x in range(100))

@garrettsmith315 Ай бұрын

A little heavy on the reverb, could use a tiny bit of bass boost to the voice as well.

@TechWithTim Ай бұрын

Agree unfortunately my recording setup isn’t the best right now as I’m moving around

@garrettsmith315 Ай бұрын

@@TechWithTim Great content thought...waiting for some Golang.....

@lesheq85 18 күн бұрын

why in 17:42 you got 16 on the first spot and the rest in order? I don't think that was supposed to happen

@kazmi401 Ай бұрын

Keyboard name please.

@mikeeotool2677 Ай бұрын

TIIIIMMMMM i copy the the script "strings that start with 'a" and end with "y" as it shows in the screen and when i run it give me 3 errors for every instance that you have "string" and asked me for "strings" and the code runned great, so I think you made 3 typos.

@jayamankrah4328 Ай бұрын

Check from your side, it might be you made the typo.

@BiologyIsHot 12 күн бұрын

The syntax for flattening a list always feels very wrong. Given that single list comprehensions put their iterable to the left, it always feels odd that for num in row is to the right of matrix. It REALLY feels like it should have been [num for num in row for row in matrix] instead of what it actually is. I actually think this is one of the worst bits of Python and I encourage people to not do these neste/unpacking list comphrensions because of how unreadable they are. It would have been great if they gave us some kind of unpacking operator syntactic sugar here with [*row for row in matrix]. That would have been a much better syntax than [item for sublist in nested_list for item in sublist]

@JosephKH.77 Ай бұрын

Should i watch harvards cs50 online?

@AlexTrusk91 Ай бұрын

yes, worst case would be entertainment & understanding concepts>hard facts. And why shouldn't you just go for it, it's free of charge

@lamborghinicentenario2497 Ай бұрын

Didn't even know this wizardry existed

@Sanjay-tiwary Ай бұрын

@CryptoBuilders Ай бұрын

is this pythonic?

@wandksitesupport2777 16 күн бұрын

i like to watch your video especially in coursecareer im trying to get a job with software engeneer

@newh1ve39 Ай бұрын

I understand the intention… but I dont understand why you dont show the differences in execution time. If there is no difference its not worth it at the moment in my opinion.

@HarnessedGnat 17 күн бұрын

It’s been pointed out in other comments that comprehensions are faster…. Someone suggested Time.perf_counter() Programmers reading code efficiently (see what’s written, faster and more reliably) has value too.

@LiamInviteMelonTee 12 күн бұрын

I guess this is mostly about readability, the performance increase varies from version to version of python (just got a boost in 3.12, see mcoding's video)