What I love f-strings for the most is padding my strings. Not only can I do a left align or right align, I can also do a center align, and give it a particular padding character. x = 'test' f'{x:>10}' → ' test' f'{x:*
@sadhlife3 жыл бұрын
most of this information comes from pyformat info, great website
@sadhlife3 жыл бұрын
@@Imperial_Squid do it :D
@stillww3 жыл бұрын
This should have been in the video it's super useful
@snippletrap3 жыл бұрын
Also useful for float formatting
@islandcave87383 жыл бұрын
Thanks for the tips.
@Vogel423 жыл бұрын
i love how fstring can convert between bases really easily: >>> a = 42 >>> f"{a:x}" # hex '2a' >>> f"{a:X}" # hex (uppercase) '2A' >>> f"{a:b}" # binary '101010' >>> f"{a:c}" # ascii '*' >>> f"{a:o}" # octal '52' >>> f"{a:010b}" # combined with padding '0000101010'
@felipevasconcelos67363 жыл бұрын
I wish I could convert to an arbitrary base just as easily. I use seximal a lot, that would certainly help.
@@definesigint2823, does it work with non-integer bases?
@definesigint28233 жыл бұрын
@@felipevasconcelos6736 _That_ is an interesting question. Numpy is int 2-36, but *Google* _"Numeral systems with non-integer bases"_ and (Reddit thread) there are several examples in the comments (e.g.): ~ Phinary (golden ratio base) ~ refs to Knuth's The Art of Computer Programming (negative and irrational bases), ~ quater-imaginary (base 2i) ~ a link that has Wolfram Alpha do a non-integer base ...hope that helps.
@felipevasconcelos67363 жыл бұрын
@@definesigint2823 there’s a KZbin channel called imaginarybinary that showcases a different flavor of base 2i. It’s criminally underrated, last time I checked the whole channel had one comment, and it was mine.
@DanielLavedoniodeLima_DLL3 жыл бұрын
Also, if you use "%" instead of "f" in the float formatting, it will calculate the percentage and add a "%" at the end. For example: >>> x = 1/3 >>> print(f"{x = :.2%}") x = 33.33%
@xakkep90003 жыл бұрын
You definitely blew my mind!
@pranavnyavanandi97102 жыл бұрын
Damnnn noice.
@johnathancorgan39943 жыл бұрын
I've learned more about f-strings from this video (and comments!) than from the intro documentation. Nice job.
@plagiats3 жыл бұрын
4:44 this is useful when you are interfacing with an old system that doesn't support utf-8
@mCoding3 жыл бұрын
I'm very fortunate that I don't have to do this! Thanks for sharing!
@xBaphometHx2 жыл бұрын
This is the best Python YT channel for tips and tricks. Glad I found it! EDIT: Another thing I learned recently is that you can pass the spaces you want to add between strings inside of the curly brackets. Example: f"{variable1:{10}} {variable2:{10}} {variable3}" That will add a 10 characters limit for variable1 and variable2, so everything looks properly formatted.
@Norsilca2 жыл бұрын
I think by "limit" you mean "minimum". It looks like this is the equivalent of f"{variable1:10} {variable2:10} {variable3}" (without the curly braces).
@sgian_ime3 жыл бұрын
Thanks James, this video was really interesting! I’m currently designing a really basic beginner python course for a local high school and your videos are definitely a source of inspiration. Keep up the great work :)
@mCoding3 жыл бұрын
Awesome! Glad to provide inspiration. Feel free to assign my videos for extra credit 😉
@rogervanbommel10863 жыл бұрын
@@mCoding $python3 -c ‘print(“same, you are a very good resource”)’ same, you are a very good resource $
@PythonisLove3 жыл бұрын
I often use f-strings to tabulate my data...and this tabulation helps when I am trying not to use library for the purpose. f'{something:50}{another_one:5}' like this!
@JEffinger3 жыл бұрын
f strings are my favorite addition to python since I've started using it.
@Claxiux2 жыл бұрын
Good vid, would like to add that you can now add thousands separators to numbers you print by doing: print(f'{num:,}') gives you something like 1,000,000
@jonragnarsson3 жыл бұрын
I can not get over the 'dunder' phrase. All I can think of is The Office.
@inigo87403 жыл бұрын
__Mifflin this is Pam.
@Amipotsophspond3 жыл бұрын
yeah, but not in a good way, I don't like it. it seems like jargon. so you have this whole language that can't stand Curly brackets because it looks not like natural language text. Yet then it starts using __init__ instead of the word constructor or Initialize or even just init or con. same with Decorators why @ when it should be dec or "dec nameofdec:" then indented "def thefunctoDec():" or "dec nameofdec(def functodec())", or just "nameofdec(def thefunctoDec():)" these would make it easier to guess out what a Decorators is doing, if you have never seen it. the Decorator looks like a function that is taking in this function I define. it's kind of like a the same as a lambda but bigger. pythonic only cares about readability when you do something complex, but if you talk about getting rid of their jargon syntax sugar to make things more readable they complain about their fingers breaking from extra typing. personalty I find Curly brackets more readable because you are not depending on unseen spaces but I understand they are not to python's style. just saying dunder __ __ has never seemed pythonic and should be replaced. even if it breaks old code because python does not care about breaking old code, it's why python 2 still is a thing.
@islandcave87383 жыл бұрын
"Good for debugging", you said the same thing I was thinking.
@vasiliynkudryavtsev3 жыл бұрын
F-string is essentially like F-word, very very cool language feature.
@tuck17262 жыл бұрын
F-string is the closest younger sibling to the g-string
@bendiknyheim69362 жыл бұрын
Saw the title, thought "huh, what else could there possibly be". Needless to say I learned some useful things
@Enthos22 жыл бұрын
All these were useful but the equals sign trick at the beginning will save me SO much time I immediately thought wow that's amazing for debugging and then you said the same thing right after. Thank you!
@WilliamAndrea3 жыл бұрын
ascii() is useful for identifying Unicode "confusables", like the Cyrillic "A". >>> 'А' == 'A' False >>> print(ascii("'А' == 'A'")) "'\u0410' == 'A'"
@tristanbroad79153 жыл бұрын
print(f' Start Price {sp:.9f}. Current Price {cp:.9f}. Change {per:.2f}%.') Thanks For the tip this makes my life much better, Also i just found you and you introduced me to dataclasses dataclass making you my new favorite person :D
@Jaun_3 жыл бұрын
Great video as always - In light of debugging, a great module I’ve been using is “icecream” - high recommend, it has the similar effect to the equals within the f-string.
@mCoding3 жыл бұрын
Cool, thanks for sharing!
@DrorF2 жыл бұрын
This little *f"{var=}"* trick is GOLD!!
@peschebichsu3 жыл бұрын
Wow nice, I just saw the part with {x=} recently in one of your videos and was using it already quite a lot since. Amazing you made a whole video about it
@alejandrocarvajal90683 жыл бұрын
basically, you can use the formating for types in fstring as it was used with .format for previous versions of python, but the advantage is that fstring is a little faster. more information can be found in PEP 498 -- Literal String Interpolation.
@xmesones2 жыл бұрын
WOW great video! using f-strings ------------------------- age = 21 def p(val): print(f'{val=}') p(age) -------------------------- it's possible to show up the argument (age = 21) instead, the parameter (val = 21)
@pizzarella9852 жыл бұрын
3:32 I recommend holding down ctrl when erasing or jumping over a word, it's really useful!
@andrey2001v3 жыл бұрын
Thank you for saving a few days of my life that I would've spent on debugging
@EsaKarjalainen2 жыл бұрын
Caveat: {equal_sign=} ignores escape characters such as For an example: >>> foo 'stuff and things' >>> print(f"{foo}") stuff and things >>> print(f"{foo=}") foo='stuff and things'
@mCoding2 жыл бұрын
I briefly mention this difference in the video. This is because f'{foo}' uses the str of foo, whereas f'{foo=}' uses the repr of foo. The repr of a str shows escaped characters, so that explains it!
@ZeroSleap2 жыл бұрын
For f-strings,when you use the walrus operator(for whatever reason) you have to put parentheses around the expression for it to work.
@houssem0092 жыл бұрын
I've been looking for the wrapper thing for days thanks
@devworks8787 Жыл бұрын
Wow. lot of functionalities packed!
@usafa19873 жыл бұрын
4:44 this is useful when you are using CircuitPython on a microcontroller and driving an LCD display that doesn’t support Unicode
@KryptoKiddi3 жыл бұрын
Or when your using user input that will later be called.. it ensures the application will display it properly
@lifelikepixel3 жыл бұрын
the = sign after the string blew my mind haha Thanks!
@DoggoYT3 жыл бұрын
geez this is actually useful. i would always write __repr__ methods like ` return f"classname('value1={self.value1},'value2'={self.value2})" ` the equals would make this so much easier
@patrikjankovics21132 жыл бұрын
Wouldn't that include the `self.` prefix as well though?
@chonchjohnch3 жыл бұрын
I took a hiatus from python from about 2017 to just recently and lord do I love this things
@murirokcs55183 жыл бұрын
f'{val =}' has been very very useful, thank you!!!
@mCoding3 жыл бұрын
Very welcome 😀
@johnr39363 жыл бұрын
You rock!! Just changed the way I write code going forward. Man I love this channel, love this info.
@USMColdies2 жыл бұрын
Everytime I think I have a handle on Python, you burst my bubble with something new
@Veptis2 жыл бұрын
You can not only nest f-strings but also make a whole table with one. Think about `a=f"{{}*3}"` and now is the question of what happens when you have something like `b=[0,2,4]` and then `a.format(*b)` Also f-strings can be used outside of print statements. Great for concatenating stuff.
@andrewglick62793 жыл бұрын
I have long loved f-strings, but I never knew how cool they *actually* are. This is great, thanks! Any chance you're working on a video about the @overload decorator? I have been very confused about the documentation I've read and knowing your style, I think you could explain it really well!
@mCoding3 жыл бұрын
I vaguely remember using it in one of my previous videos already... but which one I don't remember. Taking a break on typing related content for a while, python people didn't seem to like it as much.
@andrewglick62793 жыл бұрын
@@mCoding I vaguely remember something about it too; I'll take a look and see if I can find it. I look forward to whatever you work on next, whether its Python or not, you have a tendency to make interesting and educational content!
@guyindisguise3 жыл бұрын
@@mCoding typing related content is awesome! though to be fair pretty much all your Python content is awesome ;)
@homosapienfactory62912 жыл бұрын
kzbin.info/www/bejne/r4jdfpyXptOjoas
@homosapienfactory62912 жыл бұрын
Oh nvm you already found it lol
@douglaswolfen7820 Жыл бұрын
I'm gonna find "!s" really useful. I often have integers in my f-strings, and then I want to use the format-modifiers to modify the resulting strings (usually to left-pad the number with spaces or with zeros) I've been writing a lot of code like `f"{str(my_num):
@Bretinator2 жыл бұрын
At around 5:10, you said !s would be the default. I played around a bit and found that this is not quite correct. What seems to happen under the hood is that the curly braces around an expression "return" something like format(bangfunc(expression), format_spec), where bangfunc is indeed determined by the char after the bang. But if the bang is absent, bangfunc "defaults to the identity" and NOT to str. format_spec is the plaintext after the colon as a string and defaults to an empty string if the colon is absent. As the outer function, format will always call type(bangfunc(expr)).__format__, which only equals type(expr).__format__ IF the bang is absent. Therefore, the format_spec must fit to the type of what bangfunc returns to avoid raising an exception. So the reason why {expr} and {expr!s} behave the same in most cases is NOT because they do the same thing: for {expr}, bangfunc will be irrelevant because no bang is specified. format will then be called on expr with an empty format_spec. If type(expr) or one of its user-defined bases had defined __format__, it might do arbitrary stuff, but if not, object.__format__(expr, "") will just return str(expr). for {expr!s}, str is the bangfunc, so first, str(expr) will be called, which returns a string, lets call it 'stri. THEN format will be called as str.__format__(stri, ""), which defaults to returning stri itself. So basically, {expr} and {expr!s} will in general not behave the same as soon as the class of the object returned by the expression uses a __format__ that does not behave like __str__ if the format_spec argument is an empty string. I'm aware that these are unrealistic edge cases, but investigating this provided an even deeper understanding for me of how fstrings, format, str and repr are related and implemented.
@mCoding2 жыл бұрын
Firstly i commend you for this investigation and for taking the time to present your findings. Indeed, my explanation covers only the simple case and excludes discussion of these edge cases which I think are uncommon in real code. Indeed, practically every explanatory video I make could be wrong if the user decided to modify a metaclass, change an element of the builtins module, or use a C extension module because Python is so dynamic. I'll still try to keep things to the most common useful cases on screen, but I'm glad your comment is here for people that want to understand more as you have done. Keep up your inquisitive nature, it will take you far!
@Bretinator2 жыл бұрын
@@mCoding Thanks for your kind reply! I really enjoy your videos, it often feels like you manage to see the whole language as just one big picture, with all its countless interactions of which you never lose track or misinterpret since you truly understand what they're built upon. And therefore you know exactly what causes the most headaches for people who only have a shallow understanding of whats going on. I feel like many developers never achieved this or even tried to, because they only see the language as a tool they have to handle "just good enough" and it stays more like countless mosaics loosely glued together, with many links missing, rather than eventually becoming that big picture. I also aim for that big picture in everything I try to learn, since only then the process feels satisfying. I guess the inquisitive nature goes hand in hand with that "restriction" :) Also, one of the main reasons why I switched to software development after achieving my physics degree was because "trying out stuff" felt so much faster, which in my opinion is a crucial element for limitless self education. Anyway, keep up that great work!
@BlackHermit3 жыл бұрын
I knew of the equals sign thing, but the rest was fascinating, thanks!
@kitgary3 жыл бұрын
Really the best feature in Python 3, finally no need to use the format function.
@Roarshark122 жыл бұрын
Another home run video. I learned about {a=} and __format__(). Very useful, thanks!
@santasl3 жыл бұрын
Interesting. I did not know the additional possibilities of f-string. Thanks for pointing them out and give me a reason to revisit the python f-string page. Maybe there are further interesting ideas for how to improve my programming.
@entropicflow3 жыл бұрын
Great video as always! Keep it up! Really love the informal feel in this one, a lot like your earlier vids.
@DipietroGuido3 жыл бұрын
To all of you, the printf function from stdio.h in C has so many of these things too. You would be surprised.
@Arrowtake3 жыл бұрын
Always learning. First time I saw __format__ used and it makes sense. That's all top of the great f-string tips you had. Thanks!
@LostExcalibur3 жыл бұрын
Nice video, i learned a lot !
@chriskorfmann2 жыл бұрын
print(f"{(new_variable := 'whatever you want to assign to new_variable') = }") >>> (new_variable := 'whatever you want to assign to new_variable') = 'whatever you want to assign to new_variable' print(f"{(now := datetime.now()): %y-%m-%d}") >>> 22-05-15 ^ these actually work. I don't know how or why I would ever use assignment expressions in f-strings but I am now determined to include it _somewhere_ in my code.
@PanduPoluan Жыл бұрын
Don't forget that the "f" prefix also works with triple-quoted string.
@MakinBacon0651 Жыл бұрын
I was so excided when I learned about f-strings while skimming the notes on the 3.6 release. I may or may not have gone into all my code and replaced every format() I could find.
@jewpcabra6663 жыл бұрын
This was such a useful and awesome video! I love f-strings so this is super useful to know about. Thanks!
@KryptoKiddi3 жыл бұрын
The most useful one for me is ‘!a’ since it will allow me to fine the unicode/short code so the user or I can use it for some functions or features that may not work well with the actual emoji
@rjhornsby3 жыл бұрын
!a could be super useful trying to debug input - including string values pasted into the code - to figure out that instead of the printable character you expected, it’s some Unicode nonsense like the double dash or fancy double quote character. Generally finding the rogue character means piping the script output to hexdump to see that you have printable ascii values surrounding some weird looking multibyte sequence that doesn’t make sense like x41 x81 xe0 x43 (made up Unicode value, no idea what it is) You can try to string compare that to “ABC” all day long. It might render visually like “ABC” but it’s not ascii ABC. Can see !a as a useful tool here.
@mCoding3 жыл бұрын
That's a good point, I never thought about that but you're totally right!
@Richard_GIS2 жыл бұрын
Again learnd a lot in 9:09 min, thy -great channel
@georgesanderson9183 жыл бұрын
A new mCoding video makes my day!
@mCoding3 жыл бұрын
And comments like yours make my day!
@manofqwerty2 жыл бұрын
The date formatting is an amazing trick, thanks
@eyausoj2065 Жыл бұрын
I fall asleep to these videos 👍 cured my insomnia 👍
@definesigint28233 жыл бұрын
For anyone interested, string interpolation is documented in Python's *PEP-498* Here's a question / answer pair to research how fstrings are implemented in Python's source: _comments block links so at stackoverflow-dot-com:_ */questions/56635686/how-where-are-fstrings-implemented*
@NeilMarcellini3 жыл бұрын
1:02 is exactly what I’ve been looking for!!
@indranildas95652 жыл бұрын
f strings is one of my favourite things in python
@IndellableHatesHandles3 жыл бұрын
Every time I think I know Python, I find something I had no clue about.
@quantumastrologer55992 жыл бұрын
Spooky magic fstrings (great video!)
@justinfuruness79543 жыл бұрын
Blown away. How did you come across this stuff?
@powder_toy2 жыл бұрын
i watched this for fun but it actually helped I was writing a programing language in python so it is very text based
@fadeoffical_3 жыл бұрын
Even tho I never use python, I still enjoy watching your videos))
@cerealport27262 жыл бұрын
I sometimes use f-strings to print results of a process to a file, it's like a cheats way of sending data to a CSV file. I imagine it isn't efficient, but it does the job when you don't have much data, but want to use the output file to check results.
@stevecarter88103 жыл бұрын
So wtf is the encoding of the hex string in !a? Presumably the unicode code point or its internal encoding? Regardless, its useful figuring out what character was actually received when you can't really tell by looking, e.g. Because your console can't display it or it looks similar to another character (X vs Greek chi, etc)
@KryptoKiddi3 жыл бұрын
It’s unicode. I use it for properly displaying emojis
@aaronm66753 жыл бұрын
Loooove f-strings, love the vid, love the channel 🤠
@TheTilpo3 жыл бұрын
Some terminals don't support unicode, I think that's the main use case of `!a`
@KryptoKiddi3 жыл бұрын
Some functions don’t play well with them either so it will help in formatting it for them as well
@Lolwutdesu90003 жыл бұрын
This is really awesome stuff, thanks for sharing it!
@mCoding3 жыл бұрын
My pleasure!
@SusanAmberBruce2 жыл бұрын
Cool! I do like the more informal style thanks
@itzblinkzy17283 жыл бұрын
Didn't know you could do this with f-strings, good video :)
@whydontiknowthat3 жыл бұрын
I would have liked to have seen an example using bang s and dunder format at the same time, since you said the point of it was that it does its thing before the format codes. Still, great video!
@alperengencoglu53673 жыл бұрын
Nice video. Did you forget to talk about nested formatting in the end?
@shashishekhar---- Жыл бұрын
Thank. You so much for all these
@blzr3 жыл бұрын
You can just open doc 2.4.3 and read few paragraphs. {x=} format was added in 3.8 only
@ashishjain5183 жыл бұрын
This video is soooo much helpful... So glad I found your channel😄😄
@piotr7802 жыл бұрын
Repr is useful when using print for debugging and logs
@apetrenko_ai2 жыл бұрын
Amazing! Didn't know half of that!
@Galakyllz2 жыл бұрын
I wish there was a convenient way to print out "is None", "= [some non-string value]", or '= "[some string value]" ' (note the double quotation marks). Example (if I could make the ~ character do this): test = None print(f"{test=~}") prints out: test is None test = 5 print(f"{test=~}") prints out: test = 5 test = "here" print(f"{test=~}") prints out: test = "here"
@CoderrX2 жыл бұрын
Awesome work Loved it!
@vvvv-lo8or3 жыл бұрын
I feel like Python is your Girlfriend and you know all the tiny little secrets about it😅
@axelnils3 жыл бұрын
”it”
@VoltageLP3 жыл бұрын
that's creepy
@Xiph19803 жыл бұрын
You think you'll ever get to know all the tiny little secrets of a girlfriend? That's cute... 🤣 ... Also, a bit creepy.
@obed8182 жыл бұрын
@@Xiph1980 haha yeah
@ananttiwari13372 жыл бұрын
uhh... her? 😂
@_kopiter_3 жыл бұрын
yess, this is exactly what was separating me from being an Ultra programmer! a good video btw :)
@mCoding3 жыл бұрын
Glad you enjoyed it!
@SUPERustam3 жыл бұрын
f’str_value!a’ this case needed for see how string would look like in URL. In URL all non-ASCII symbols will convert to smth like this /U73937489. This is my Thought 😀
@cmyk89643 жыл бұрын
URL encoding is a lot different. Every illegal character is encoded as UTF-8 and the bytes listed in hex after a %, or in the case of “--xn” encoding, some complex stuff that I can’t really explain.
@robertbrummayer49083 жыл бұрын
Great job! Your videos are excellent. I enjoy them a lot.
@mCoding3 жыл бұрын
Thank you very much!
@MrSteini1243 жыл бұрын
Fantastic video, love these fundamentals
@mydetlef Жыл бұрын
I'm looking for a way to teach f-strings to use locale. I get from print(f'{1400.0:,.2f}') -> 1,400.00 but I haven't found a way to get something like the German format 1.400,00 through configuration. Of course, I can create the string myself using the locale module, but that means changing all f-strings. Anyone have a suggestion/link?
@pemessh3 жыл бұрын
That = trick would be really handy.
@Noritoshi-r8m2 жыл бұрын
Grateful, very useful
@Omena0 Жыл бұрын
Why didint you do all of the formatting stuff like alignment and making sure all of ur print statements print the same length even with diffrent variables Eg f"{var:
@UnfamiliarPlace2 жыл бұрын
>>> num = 1000000 >>> print(f'{num :,}') 1,000,000 >>> num = 5 >>> print(f'{num:0>3}') 005
@adamquek10953 жыл бұрын
Cool tips. Thanks!
@Repligon3 жыл бұрын
I still remember how I made a large script with lots of logs, formatted with f-strings. Then I uploaded it on a server and subsequently had to replace all of them with explicit 'format' statements because server was running Ubuntu.
@mCoding3 жыл бұрын
This seems like more of a version of Python problem and less an ubuntu problem. Well I suppose you may not have had access to upgrade the Python so I guess that's fair. Always good to keep in mind what software your system has.
@Repligon3 жыл бұрын
@@mCoding I think, it took them almost a year to finally upgrade to python 3.6. But yes, it is a version problem that I encounter pretty frequently with Debian based distros.
@rickharold78842 жыл бұрын
Beautiful
@MisterDan2 жыл бұрын
nicely explained
@carsten_3 жыл бұрын
f'{str_value=}' especially if persist over function scopes, looks like it has some potential for security issues 🤔
@victornoagbodji3 жыл бұрын
Thanks so much for going over these f-string features. Very concise video 😊🙏😊🙏
@mCoding3 жыл бұрын
Glad it was helpful!
@VladyslavHladchenko3 жыл бұрын
extra nice !
@eulefranz9443 жыл бұрын
Oh my god thank you!!
@songokussj4cz3 жыл бұрын
Ah. f-strings. They are eeeeasy. Rolling them for years with all the tricks... Literally first tip at 0:50 *surprised pikachu*