CS50W - Lecture 2 - Python

[@anaveronicaaponte]

It's always great to refresh some concepts like classes, lambda functions and decorators. Thanks Brian and the CS50W's team!

[@cje8887]

Great lecture! I was already somewhat familiar with Python, but Brian's explanations of decorators and lambda functions really helped me understand them better

[@blabla-kk8bl]

you never need them.just making more complex. simple is better than complex.

[@stacy3781]

Brian's presentation was so engaging and clear that 1 hour flew by so fast!

[@compilerrun5516]

Man your typing speed 🔥.

[@christoffer6527]

The coding software has autocomplete

[@IXITHELEGEND]

Looks even quicker at 2x speed

[@mo.G_2020]

​@@christoffer6527nope, he can touchtype fluently

[@alexrubio9507]

of course it does, but he doesn't use autocomplete all the time, and even if he did, STILL...the typing process speed is purely amazing, you can't deny that.@@christoffer6527

[@kaustubhkadam1083]

he also uses vim motions in vscode

[@joseignacioyanez572]

Brian, thanks for being such a great Teacher! I've seen other videos on decorators and it seemed so difficutl to understand, but in a couple of minuts you explained it and made it look so easy and clear, I was smiling haha. Thanks to you, David and all the team!

[@sayori3939]

It's interesting the fact that throughout the 4 cs50 courses we see python used in different perspectives

[@smileorcry7204]

Python is in everything now😅

[@sayori3939]

@@smileorcry7204 if you use linux python will end up installed on your system no matter what, it's like baidu but actually useful

[@anuradhamangalpalli2774]

Thank you, Brian. This is the first time I understood python fundamentals.

[@kavya0102]

Very succinctly but clearly explained. A good refresher for Python. Thanks!

[@thomastan9901]

You are an excellent lecturer. No text book is needed

[@MrRynRules]

Great lecture! Learned a lot even hough i have been coding python for the last 2 years

[@PeterBohai]

Loving the Harry Potter references. Great lecture as always!

[@shrikantdhayje3490]

finally got a tutorial which also explains the compiler errors also. thank you so much! Great lecture

[@zerodivided3676]

Take a shot whenever Brian says ' for example' :) Nice and fast python introduction though.

[@Komikkopeksevdalisi]

Gerçekten harika çok kısa bir sürede bütün önemli olan bilgileri veriyor. Keşke programlamaya ilk başladığımda bu eğitimi izleseydim, diğer eğitimler uzun ve gereksiz bilgileri verirken en önemli olanları vermiyorlar.

[@d0tjs]

has been a great refresher on python

[@kenmwendwa1882]

I loved the object orientated programming and decorator explanation

[@facts6824]

haward University admission via youtube....superb no assignment no submission

[@aryansharma4775]

you can find assignment notes and project at edx for free

[@lishichan3365]

The actual course is on edx these are just lectures

[@LEVIACKERMAN-mg4cp]

@@lishichan3365 isn't this lecture not enough?? Or the course is much helpful? I mean if I didn't enrol to the course will i miss any lectures on there that is not available on youtube?

[@sayori3939]

@@LEVIACKERMAN-mg4cp you'll miss the problem sets which are the 2nd most important things in this course and you won't get havard's free certificate (NOT THE EDX ONE)

[@Wawazi]

Never imagined Harry potter would be pivotal to my learning

[@adforknowledge6582]

:P :D Me too was shocked to see it and loved it a lot... That too , Brian is like superb awesome person he kept his face blank just looked at the audience for 1 sec from the corner of the eye and started typing Harry , Harmoine ha ha ha .. That was super awesome moment .. I started smiling .... :P :)

[@Wawazi]

@@adforknowledge6582 I doubt if anyone didn't smile at that moment. Completely epic stuff!!!

[@thiagobarso]

😹

[@meruem6995ujjoooo]

Yer a coder Phillip

[@Hackonomics]

Love you Brian brother!😍 You're clear my all concepts!

[@northstarcode8675]

Yer a wizard Brian

[@taofeekajibade]

Quite brilliant presentation. Many thanks, Brian.

[@Ldmp807]

Best way to explain decorators!

[@CW711]

Brian is awesome.

[@covingtonkua9404]

This video alone just thought me an entire sem worth of python

[@kingcogles]

After Project 1 and 2 which is Python/Django related, I need to say reading the Django docs is like getting lost in a forest. But still lovin' the fact that it is a very, very powerfull framework.

[@blazi_0]

Yea ,the documentation is worst ! It's like they wrote this documentation to make you feel that you don't know Python 🤣

[@kingcogles]

@@blazi_0 Yeah like that. I even had like 5+ tabs just of Django's docs to be able to find quickly what it might be helpful to me and most of the time for nothing. Now I started to work on Project 4 ... and you guessed it, Django has to be used. Suddenly "The sound of silence" played in my brain. 😭

[@shrikantdhayje3490]

agreed

[@sayori3939]

At this rate you're better off searching specific topics in random websites on google. You just need the right keywords

[@nawafEalharbi]

As a person who learned python before This is a really fast course about python, lets called it introduction to python is better.

[@christian37ism]

The object oriented teaching was helpful, thank you.

[@MuhammadAbbasYousafzai]

Thanks Brian

[@shubhammandal6735]

Python Classes Code: class Flight: def __init__(self, capacity): self.capacity = capacity self.passengers = [] def add_passengers(self, name): if not self.open_seats(): return False self.passengers.append(name) return True def open_seats(self): return (self.capacity - len(self.passengers)) flight = Flight(3) people = ['Harry', 'Ron', 'Hermione','Genny'] for person in people: success = flight.add_passengers(person) if success: print(f'{person} is added to the Flight') else: print(f'No, Available seats for {person}')

[@galofloresc]

I have the same code but when trying to run it an error says that Flight takes no arguments. any help

[@sukhmanpreetsingh1525]

can you paste your code here?

[@trident7996]

import random class Flight: def __init__(self, capacity): self.capacity = capacity self.passengers = [] def add_passengers(self, name): if not self.open_seats(): return False self.passengers.append(name) return True def open_seats(self): return (self.capacity - len(self.passengers)) flight = Flight(3) people = ["Harry", "Ron", "Hermione","Genny"] random.shuffle(people) for person in people: success = flight.add_passengers(person) if success: print(f"{person} is added to the Flight") else: print(f'No, Available seats for {person}')

[@trident7996]

justice for genny!!!

[@zaharaddeenkaramilawal4994]

What a wonderful presentation

[@bleulejour]

Thanks Brian, simply brilliant!

[@koushik3415]

Simple and Elegant ! 💕💕💕💕💕💕💕💕

[@abdullahgumel3936]

Our teachers told us not to use the word innit in school, now I'm level 9000 programmer I use innit when I want

[@TranNguyen-mv6ln]

Thank you so much

[@innocence3158]

Brian at the start: So this is an integer Also Brian (close to an end): this is too much of an abstraction

[@Mapleaph]

Best tut ever

[@mrgomezs]

thank you

[@bimalakumari243]

Tank you for your efforts

[@hychembek]

thanks

[@claudiamanta1943]

Thank you 😊

[@josemariarodriguez7845]

52:42 Brian combines flight, which is a variable from Class Flight , and add_passenger, which is a method from the class Flight: flight.add_passenger(person). It is pretty clear that both combined, flight and add_passenger, have the ability of looping the list people, and add the person to the flight, if the capacity is not zero. But please can anyone provide some additional abstract to this mechanism, how's called, how's work (some_variable.some_method(some_other_variable)?

[@finobialfaceoff7260]

Thank you sir !

[@ridayasin7946]

Incredible

[@emilsjoblom273]

This is the entire cs50p course in one video..

[@bakeelalnhmee1776]

Great lecture, greater lecturer

[@aljosja3353]

Thanks you!

[@ranjanasaiyam5834]

He is genius,i feel and see it

[@johnpill1]

I finally get what SwiftUI property wrappers are after using them for months thanks to the last section of this as I guess this is essentially what they are?

[@shahbazmuhammad8183]

import functions for i in range(10): print(f"The square of {i} is {square(i)}")

[@jamaka_me_code796]

With your syntax as is, it should be functions.square(i) inside the curly brace 👍 or change import to -> from functions import square

[@sayori3939]

What the hell is that "functions" module Oh i get it ._. You can import a module with an alias: "import functions as f" careful not to name it the same name as another module you're using

[@mon0theist_tv]

I think I'd rather just write a function instead of using lambda lol but Brian's explanation is the only one I've seen that kinda sorta makes sense

[@RomarioKurti28]

In the lambda example he defined a function 'f' that takes a person as an input and returns that person's name. After that he assigns the return value of that function 'f' to the 'key' attribute of the sort function. What i don't understand is how is the person passed as an input to the 'f' function during the sort execution! Thanks fo the help 😊

[@eltinahutahaean759]

It has to do with the sort method of list. Parameter key will apply a function given to it to each of the list items ``` Help on built-in function sort: sort(*, key=None, reverse=False) method of builtins.list instance Sort the list in ascending order and return None. The sort is in-place (i.e. the list itself is modified) and stable (i.e. the order of two equal elements is maintained). If a key function is given, apply it once to each list item and sort them, ascending or descending, according to their function values. The reverse flag can be set to sort in descending order. ```

[@sencode589]

Very clear and interesting! thanks!

[@_rachid]

Cool! Thanks.

[@malithsenanayakentgl-1052]

Excellent lecture. Thanks...

[@Duge6124]

is the wrapper function 57:00 really necessary. Can we not just write line 3-5 inside announce?

[@yuna_tseng]

haha I have an exactly same question here too, i use js to reproduce the situation without the wrapper function, and it works. but i think the wrapper function here brings the more powerful function like closure`s effect

[@sayori3939]

But then how would return all of that? If you tried to return "announce" it would ask for an argument and it would get a recursion error

[@gromit9826]

32:21 this type of code doesn't seem to work anymore, it just gives me a syntax error (Python 3.12.4 64-bit)

[@isha7372]

Problem sets for week 0,1,2 are same I have submitted with all specifications for week 0 do i need to submit again or just skip ?

[@smileorcry7204]

Where to find problem sets.there are only projects in cs50w course .

[@patrickb6938]

Just awesome!

[@KeyserTheRedBeard]

fantastic upload CS50. I killed the thumbs up on your video. Maintain up the wonderful work.

[@bangtanffarmy]

6:53 the code shows an error in the terminal after I put xyz name in input (terminal), it says NameError: name 'xyz' is not defined

[@lautar]

No available sits for Ginny :(((((((((

[@shazkingdom1702]

😀😀😀

[@dmytrosoroka7335]

Thanks from Ukraine!

[@kimjongun3890]

🧐

[@sayori3939]

:(

[@-leovinci]

When can we introduce Common Lisp...

[@niyomungelialine6840]

what edit are you using

[@Dr.Javaidqureshi]

Pl suggest solution. both files are in the same folder PS C:\javaid\Python\Lecture1> python squares.pi Traceback (most recent call last): File "C:\javaid\Python\Lecture1\squares.pi", line 1, in import functions ModuleNotFoundError: No module named 'functions' PS C:\javaid\Python\Lecture1>

[@zizou5638]

bro the file extension is wrong it should be .py not .pi

[@jaafarhammoud7507]

how to remove the background behind him when record coding?

[@sayori3939]

Honestly i would like to know too

[@chiraglal4938]

How are you opening that terminal dialogue box?. I'm using windows btw.

[@blazi_0]

He is using Mac

[@sayori3939]

What do you mean by terminal dialogue? :0 you can execute "cmd.exe" in windows and execute your python programs there (if you have it installed properly)

[@ivankoh3779]

Why are we relearning python? Isn't this alrd in CS50?

[@animeshdas6866]

This one is more focused on web development.

[@shahbazmuhammad8183]

def square(x): return x * x

[@sayori3939]

Those decorators are so confusing '~'

[@hizkiapermata5206]

Finally

[@admasuchane2402]

can we develop a web application for multilevel marketing(MLM) using python????????????

[@codegoblin7740]

nah you need assembly for that.

[@divyanshjainbhajan]

What's that application in which he runs is program? One with the black background.

[@green--apple]

That's the Terminal. Every computer has one.

[@divyanshjainbhajan]

@@green--apple like command prompt?

[@AmitTiwari-wf1xj]

@@divyanshjainbhajan yes

[@csgundee]

You can use VS code terminal instead of the black one.

[@bvedantcodes]

@@divyanshjainbhajan Command Prompt is exclusive to Windows. I'd recommend installing Bash via Git Bash or Windows Subsystem for Linux-- the commands here are shared with the command line in macOS and Linux operating systems

[@jayanthbharadwaj2041]

Where can i next best course on Python!!..thanx for the introductive course 😊

[@JT-iv8nd]

5:59 If input does not work try raw_input

[@sayori3939]

If input is not working you probably don't have python set up properly or have some sketchy python interpreter/library

[@sherxon1217]

that is good 👍👍👍👍👍👍👍👍👍

[@v.calipso7687]

senk you

[@jjjjjly]

I missed the animation some professors made to help us to understand Pointer in cs50x. Decorators are honestly little hard for me.

[@justinbieber9656]

Is this lecture content any different from CS50s week 7 Python lectures?

[@jakubpietrzak70]

Yes, you can look it up in video description

[@Itinerant_Indian]

Not so much

[@sayori3939]

Dude cs50x python lecture was a true killer, it taught me more than a whole course, maybe because i was fresh with C but man that was awesome

[@joseignacioyanez572]

Yes, especially the second half, OOP and Functional Programming, such a great explanation

[@harshalsonawane8879]

Which compiler he is using

[@kimjongun3890]

vs code

[@sayori3939]

There are no compilers :0

[@mohammadshoaib5881]

When the projects will be available?

[@kingcogles]

They are available on Edx for free, so hurry up, last date for submission of all projects is December 31 this year.

[@mohammadshoaib5881]

When will the projects be availabe for cs50 web programming 2020?

[@gabemvp]

The new projects will be available on July 1st, as published on the course webpage on edX.

[@ruleoflawedutainment]

Under the flight example, I get error message which says flight = Flight (3) TypeError: Flight() takes no arguments. Any help please...

[@icy1018]

In your __init__, you probably just have __init__(self). In the case where it’s __init__(self), you would reference it by flight = Flight() but instead you provide a parameter. You would need __init__(self, capacity) to reference it like flight = Flight(3)

[@galofloresc]

@@icy1018 I have the same issue but I double checked and it says _init_(self, capacity): still showing the TypeError that takes no arguments. any help?

[@icy1018]

@@galofloresc double underscore for the init!

[@galofloresc]

@@icy1018 totally missed that, thanks!

[@boluomiable]

i was watching the old (2018) one in June, so the update of July will not have flask?

[@bvedantcodes]

Yeah, they're going with Django instead

[@boluomiable]

@@bvedantcodes thx

[@bvedantcodes]

Anyone know what vscode theme he's using?

[@lukealadeen7836]

Not vscode it's cs50 ide

[@bvedantcodes]

@@lukealadeen7836 😂

[@wanglan4255]

more like a show

[@sanchitjaiswal2979]

poor Ginny, she got left out

[@nataliehill5899]

54:52 decorator

[@tams805]

If anyone is trying to set up Notepad++ on Windows for this, then aipython has a good video called "Python and Notepad++ | Running python code from Notepad++ | Python Tips 2". Python 3.11 is probably installed in "username > AppData > Programs".

[@mrgomezs]

apologetic declaration against intelligencers

[@shrikantdhayje3490]

what!

[@mrgomezs]

outwitting the devil

[@mrgomezs]

read

[@sayori3939]

what!

[@parulgupta572]

Hi, for what is 'f' used in python?

[@freelanceprogrammer9537]

format

[@rahulanand6015]

i was wondering about the same thing as well

[@icy1018]

@@rahulanand6015 it’s called an f string which is just easy to use. The old way to format a string was: name = “Billy” print(“Hello %s” %name) That would print Hello Billy but it can get confusing really fast. There is also the .format shown below: name = “Billy” print(“Hello {}”.format(name)) .format also is old and can get confusing since you may have many entries in the .format and it will take time to see which parameter goes where. Nowadays, the f string is used. Example: name = “Billy” print(f”Hello {name}”) You can probably see how useful that can be and clean it looks. Definitely helps readability. Hope that helps

[@rahulanand6015]

@@icy1018 thanks a lot mate its really a great explanation

[@icy1018]

@@rahulanand6015 Glad it helped

[@miquelstrippoli2286]

Python is like Java but much more easy

[@nawafEalharbi]

Every thing in Python so easy until we come to OO 🙂.

[@excelvbaselftaught889]

If you don't know any other language, then Python is very easy because it's extremely logical, as a human might think. However, if you are coming from a language like C, JavaScript, or Java, it's actually more difficult to pick up Python initially because you have to "unlearn". Parentheses (), square brackets [], and squiggly brackets {} mean something totally different. OO is a set of paradigms that, once learned, port relatively easily. C does not support objects natively.

[@andiuptown1711]

@@excelvbaselftaught889*Actually, it’s quite easy. Things like brackets and semicolons are so trivial lol*

[@parulgupta572]

46:45 I didn;t understand what point is !!! and what is ' IN__IT"

[@freelanceprogrammer9537]

__init__ function initializer, theory say... called a constructor, or initializer, and is automatically called when you create a new instance of a class

[@sayori3939]

You butchered that word lol

[@SoupsIsNicer]

Think

[@fabioaugusto9866]

tem em PT BR?

[@sayori3939]

Infelizmente nao :/ mas pesquisa, de repente tem alguma versao legendada

[@Ryokans]

Brian is so mature, but he has a babyface... hard to tell how old he is 🤔

[@brunomattesco]

he's thirteen

[@DesazMusicYt]

Second part of video...I understood NOTHING

[@rohankumarcl8852]

Excellent lecture. But it would be better if you explained while loop.

[@desianaginting3741]

I'm new in Phyton. Where i can download Phyton for free? Which text editor i can use for phyton?

[@davidjmalan]

You can use cs50.dev/!