Here are my top 5 most useful f-string formatting tricks that I use everyday in Python. ▶ Valentine's Day SALE on indently.io: www.indently.io ▶ Follow me on Instagram: / indentlyreels
@Naej7 I don't think so, many people choose Python for its simplicity, with the absence of type annotations being one of the key factors. Removing this feature might deter beginners from trying it out. However, as you become more proficient in programming, you may choose to utilize type annotations or when exploring other languages.
@@_Loki__Odinson_ Type Annotations help a lot, and if adding 5 characters (: int) is too hard at the beginning, then one should give up on programming lmao
@@Naej7 Except people don't understand how to use them, so you end up with unnecessarily hard to use APIs. If that's how you feel, why not just use C? 🤦♂️
About the fourth trick: the f in ".2f" tells it to format as float. You can also do for example ".2e"" which will format the number in scientific format.
Great video! I missed the bonus tip where you explain that format string calls __format__ on the object being formatted, so you can do your own formatting, like this: class MyData: def __init__(self, a: int, b: int, c: int): self.a = a self.b = b self.c = c def __format__(self, spec): if spec[0] not in self.__dict__: sep = spec[0] l = list(spec[1:]) else: sep = ',' l = list(spec) return sep.join(str(self.__dict__[key]) for key in l) my_var = MyData(a=1, b=2, c=3) assert f"{my_var:cba}" == "3,2,1" assert f"{my_var:-abc}" == "1-2-3"
i knew last one already, but seeing it again made me realise i should try to do this in java too, would have shortened a whole lot of cruft in one program i made.
the thumbnail to this video inspired an idea to use format strings in dictionaries so that a dynamic series of texts can undergo a linear list of mutations. Honestly, I actually need to refine my idea though.
My preference is th .format(...) method fo a couple o reasons. I use Micropython a lot and f""" is not or has not been available, for format supports all the styles I like. i8n the string being formatted is not known at development time. Scope, the names using inside the string can be assigned at use time, i.e. in a function the value may be in a variable gmt_time but the string uses a standard name 'time'.
I wish more languages would copy this feature, and that Python would allow you to use variables inside the strings to select formatting options. For my own language, I made all strings f-strings and just have a shorthand where "$var" will stringify the value of `var`, and "${ expr }" will stringify the value of any valid expression. I made it so that format specifiers could use a variable instead of a numeric constant in the string. That way you could pad the output to the terminal dependent on the actual terminal attributes without using a loop. I'm hoping that this methodology negates the need for *printf() functions in my language, because separating the variable from any formatting options on it is error prone, and most of the time people just want to print as is.
Does datetime have a formating depending on nation? Like we would have already through a login or a whois access to a users current or defined whereabouts or nationality and we would want to have their specific way of reading time provided for them.
Hey bro, can you make an easy to digest about python Decorator I've been stuck in this topic for about 2weeks, all the video that i've watched are still hard to digest for my brain I would be glad since you've shown me this cool F-string trick that i never knew existed Thank's in advance
A decorator is a syntactic sugar for setting a variable of the same name to the result of applying a fucntion to a function. @decorator1 def func(): ... Is the same as: def func(): ... func = decorator1(func) The key here is that decorator1 _must_ return something that is (1) callable, and (2) has the same arguments as the function it wraps around.
It allows him to specify what type of variable it is. "n: int = " tells anyone reading that it's an integer. I'm glad you asked that though, because I'm an amateur and I'm curious, @Indently is that common practice?
Hi! Thanks! Great video! Worth mentioning that the last one does not work on older versions of python3 (I tried it on 3.7.17 and it gives a syntax error).
9:30 that approach though had the single quotation marks removed, which from a formating pov is cleaner, isn't there a version of the first shorter approach without the quotation marks then printed? (edit: while still being flexible in terms of variable names as mentioned)
What can you do with print(f'{var: >+{x}}') ? The additional + get's printed in front of var but a - doesn't, you can put a # instead of the + and it's not throwing an error, yet doesn't seem to do anything. Letters and other symbols give an error.
i dont really know anything about programming or python but im curious. when you do "var:" is the colon part of the variable name? or a requirement for specifying a variable name? if its part of its name, is it to differentiate it from something else?
The colon after a variable name is for typing the variable, for example: my_var: str = ‘Hello’ We’re saying that my_var is of type str (string) and has the value ‘Hello’. However, the typing is not necessary and my_var = ‘Hello’ would work just as well. Though, most people would recommend to use type hints
@@AnonHooman Well if assigning simple, easy-to-infer data for a variable, I usually do away with type-hinting. Type-hinting is a godsend to mark parameters to a function, preventing hard to trace ValueError or TypeError exceptions later on. I usually don't type hints my variables except when I'm doing unpacking.
Type hints or specifying types are good practice, rather than commenting what should be obvious code. It also enables easier linting and test suites. Google "why type hint" ❤
It's called type-hinting. In his example, it doesn't serve much. But in a big program, it will cause the IDE to warn you that you plan on using a variable only to store certain type(s) but you accidentally typed code that assign a different type to it. For instance, say you have result: string = "" Then much later on you assign: result = sorted(some_list) print(result) The IDE will warn you that, "hey, you originally said you're only going to store a string here, but let me warn you, you're about to store a list here." Other than that, Python won't actually error out there.
Another example purpose: You assign the result of a function that _declares_ it will return a list of floats def some_func() -> list[float]: ... rslt_list = some_func() Then you do this: print(", ".join(rslt_list)) The IDE will warn you that the str.join() function requires a list of str, but you're calling it with a list of floats. In this case, if you don't heed the warning, your program will raise an error at that point (because of .join()'s requirement).
Again, in all case, you're only given a hint that _probably_ something is not quite right. It still won't change Python into a statically-typed language. Just another tool to help a Python Programmer prevent errors due to Type Mismatch.
In the first example, int variable n assigned a number in scientific notation returns a float number when printed, but no error occurred. In what sense must n be declared a float therefore?
It’s not a type declaration, it’s a type hint given as an annotation. Annotations in Python have no effect at run time so no error occurs. They are just hints to a static type checker.
You need to be careful with the equal sign formatting. It is relatively new. I sometimes have to use Python 3.7 because that’s what is preinstalled and there it does not work.
@@Indently we are using Amazon Linux 2 still where it is the default. As it is only for management stuff we use the python that is available and don't install a later one. We will migrate to AL 2023 (or newer) eventually.
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the "=" trick in the f-string is fire.
It made my day - I'm gonna test run it in a loop with some random dictionary to see how many cool tricks it can do (like reading current settings) :)
ok, my idea didn't work as expected 😅
Yeah, completely agree it is amazing
Ever since I learned f-strings...I love them.
I wish I had known sooner!!
And I love you....
Sorry if I made things awkward... 😬
Oof this awkward isn't it?
I've been using python for about 10 years, and f strings extensively, but never knew that last tip! Game changer!
well, thats cause its only a very recent one (afaik)
@@yash1152it was introduced in 3.8, so a while back
This is the first time I have seen someone specify datatype for variables in python, and I honestly loved it.
Great tips btw.
That's the hype for type annotations that I love to see!
Not using type annotations should be banned by law
@Naej7 I don't think so, many people choose Python for its simplicity, with the absence of type annotations being one of the key factors. Removing this feature might deter beginners from trying it out. However, as you become more proficient in programming, you may choose to utilize type annotations or when exploring other languages.
@@_Loki__Odinson_ Type Annotations help a lot, and if adding 5 characters (: int) is too hard at the beginning, then one should give up on programming lmao
@@Naej7 Except people don't understand how to use them, so you end up with unnecessarily hard to use APIs.
If that's how you feel, why not just use C? 🤦♂️
About the fourth trick: the f in ".2f" tells it to format as float. You can also do for example ".2e"" which will format the number in scientific format.
The last one is super duper cool!
RIP the maintainer
@@dcx45 he should then watch this video
Great video! Didn't know about the datetime and debug print ones. Definitely going to use them in the future, though.
Didn't know about the date/time and equals formatting. Looks like the first one forwards to strftime. Makes things so much more concise and readable.
This kind of tips are awesone. We need more 👍
Great video! I missed the bonus tip where you explain that format string calls __format__ on the object being formatted, so you can do your own formatting, like this:
class MyData:
def __init__(self, a: int, b: int, c: int):
self.a = a
self.b = b
self.c = c
def __format__(self, spec):
if spec[0] not in self.__dict__:
sep = spec[0]
l = list(spec[1:])
else:
sep = ','
l = list(spec)
return sep.join(str(self.__dict__[key]) for key in l)
my_var = MyData(a=1, b=2, c=3)
assert f"{my_var:cba}" == "3,2,1"
assert f"{my_var:-abc}" == "1-2-3"
This is amazing!! thank you for this tutorial!!
Wow, so many simple things I didn't about... Thank you
"Simple y bello como un anillo", como diría Neruda; pero además, muy funcional. ¡Muchas gracias!
Thank you for the instructive tips!
Love your vids man! would love to see a tutorial on cython from you!
Thank you, this went STRAIGHT into my current project. Commas in numbers was one of the next things I was going to look up.
Nice and useful tricks for every day programming. I also prefer specifying types of variables, since it makes code better understandable.
Nice collection! 💯
Absolutely fantastic and useful video!
Finaly! All fstring variations in one film
Love the video I knew some of those but the last one is epic I will be using that from now on .
Love #5. Thank you.
For those who didn't know, the last one is called self-documenting expression and was released in Python 3.8
i love f strings
also this is like the 3rd time i come across the = specifier but i keep forgetting its existence and type in the whole thing
It's a cool trick for sure!
F strings are soo chef kiss
So cool.. thanks for sharing it. very informative
Loved the last trick!!!
Loved it ❤
Great video....
Thanks a lot😍👍
This is super cool, I sadly can't think of any usecases in my current project
That last one is sooo useful!
Great work sir❤
This is pure gold 🥇
thanks for the showcases
The last one was good!
Very nice. Another useful is formatting float as percent: f"{foo:.2%}".
Last trick was super cool...
i knew last one already, but seeing it again made me realise i should try to do this in java too, would have shortened a whole lot of cruft in one program i made.
Thank for nice tricks 😘
thanks for your time
please make videos about data structure
Great video. Thanks
Great video!
I like that print(f’{a + b = }’) one at the end. I can think of a few times when I’d use that.
Earlier I didn't know it worked on whole expressions, I think it's super cool as well!
Thanks very much
the last fstring was dope
Very nice
Thanks
Yep, I'm saving this video
too* 😂😂
Trick #2 is neat
I always use pyformat. Very easy to understand and pretty nice too. Var = 15
print(“this is my var: {}”.format(var))
Круто! Спасибо!
the thumbnail to this video inspired an idea to use format strings in dictionaries
so that a dynamic series of texts can undergo a linear list of mutations.
Honestly, I actually need to refine my idea though.
To use scientific notation with integers, you can either do int(2e9) or 2*10**9.
My preference is th .format(...) method fo a couple o reasons. I use Micropython a lot and f""" is not or has not been available, for format supports all the styles I like. i8n the string being formatted is not known at development time. Scope, the names using inside the string can be assigned at use time, i.e. in a function the value may be in a variable gmt_time but the string uses a standard name 'time'.
I was so stoked when f'{ var = }' was added to Python!! Might be abusing it a bit lol
These will be useful to me for sure. Here's a comment for the algorithm gods!
Nice Tricks!
ooh i like these videos
logic magic !
nice examples
Intersting, a large part of the world is using . (period) as a 1000 separator and , (comma) as a decimal point.
That last one goes wild
Klasse 😃👍
Very nice.
The last one blew my mind
Superb
Fact: You can define custom logic for f'string on your classes and get string after : as argument to __format__
You make the code easier to read, so you better use the functions of the str class! 🐳
Thank you
I wish more languages would copy this feature, and that Python would allow you to use variables inside the strings to select formatting options. For my own language, I made all strings f-strings and just have a shorthand where "$var" will stringify the value of `var`, and "${ expr }" will stringify the value of any valid expression. I made it so that format specifiers could use a variable instead of a numeric constant in the string. That way you could pad the output to the terminal dependent on the actual terminal attributes without using a loop. I'm hoping that this methodology negates the need for *printf() functions in my language, because separating the variable from any formatting options on it is error prone, and most of the time people just want to print as is.
Don't forget in newer python you can add multiple lines of text by stringing together f strings
Does datetime have a formating depending on nation?
Like we would have already through a login or a whois access to a users current or defined whereabouts or nationality and we would want to have their specific way of reading time provided for them.
This definitely seems more convenient than it is in js.
Awesome! I love the '=' and >
Apart from learning about the f condition, I also learned you can declare the data type in python which i have not been doing lol
3:24 this tip will literally improve my code quality
Hey bro, can you make an easy to digest about python Decorator
I've been stuck in this topic for about 2weeks, all the video that i've watched are still hard to digest for my brain
I would be glad since you've shown me this cool F-string trick that i never knew existed
Thank's in advance
A decorator is a syntactic sugar for setting a variable of the same name to the result of applying a fucntion to a function.
@decorator1
def func():
...
Is the same as:
def func():
...
func = decorator1(func)
The key here is that decorator1 _must_ return something that is (1) callable, and (2) has the same arguments as the function it wraps around.
I have videos about it on my channel, just search "decorators indently"
Hello @Indently,
Can you please explain me, why you use ":" after a variable for ex. n:?
Regards.
It allows him to specify what type of variable it is. "n: int = " tells anyone reading that it's an integer. I'm glad you asked that though, because I'm an amateur and I'm curious, @Indently is that common practice?
Gold!
May I ask which IDE and development env are you using? Looks so great
It’s PyCharm
@@meowsqueak thanks!
Hi! Thanks! Great video! Worth mentioning that the last one does not work on older versions of python3 (I tried it on 3.7.17 and it gives a syntax error).
Probably added in a later version. I'd love to know which. Edit: it's called self-documenting expression released in Python 3.8
This Video was sponsored by me. 💀
You're cool! 👍
9:30 that approach though had the single quotation marks removed, which from a formating pov is cleaner, isn't there a version of the first shorter approach without the quotation marks then printed? (edit: while still being flexible in terms of variable names as mentioned)
big fan bro
from india
Thanks!
rounding in python .. cool
thanks
Which editor is that? Looks fresh
What can you do with print(f'{var: >+{x}}') ?
The additional + get's printed in front of var but a - doesn't, you can put a # instead of the + and it's not throwing an error, yet doesn't seem to do anything. Letters and other symbols give an error.
i dont really know anything about programming or python but im curious. when you do "var:" is the colon part of the variable name? or a requirement for specifying a variable name? if its part of its name, is it to differentiate it from something else?
The colon after a variable name is for typing the variable, for example:
my_var: str = ‘Hello’
We’re saying that my_var is of type str (string) and has the value ‘Hello’. However, the typing is not necessary and
my_var = ‘Hello’
would work just as well. Though, most people would recommend to use type hints
@@AnonHooman Well if assigning simple, easy-to-infer data for a variable, I usually do away with type-hinting.
Type-hinting is a godsend to mark parameters to a function, preventing hard to trace ValueError or TypeError exceptions later on.
I usually don't type hints my variables except when I'm doing unpacking.
Which code editor do you use? It appears to be pycharm. But the ui is different from what I have in windows laptop.
It’s the new UI. Perhaps you’re still using the legacy UI?
For debugging, I recommend the "Icecream" library.
That last tip is the biggest argument against a debugger; if they wanted you to use it, why did they provide that debug syntax? 🤓
1e9 was the most useful to me
What does the f prefix do at the beginning of the argument? Are we inserting a blank float?
Are you talking about the f prefix before the quotes? If yes, then that's "f strings"
@@mudyeet_ yeah, like what does an 'f string' even mean? Feel like they missed out on calling it a G string
Yep, f string is a great feature. At least something Python gives us 😅
in the first example, do you know what decimal points wouldn't work?
Question. Why do you declare the variable with the type? I'm a beginner and I never saw that, it's a good practice?
Type hints or specifying types are good practice, rather than commenting what should be obvious code. It also enables easier linting and test suites. Google "why type hint" ❤
It's called type-hinting.
In his example, it doesn't serve much.
But in a big program, it will cause the IDE to warn you that you plan on using a variable only to store certain type(s) but you accidentally typed code that assign a different type to it.
For instance, say you have
result: string = ""
Then much later on you assign:
result = sorted(some_list)
print(result)
The IDE will warn you that, "hey, you originally said you're only going to store a string here, but let me warn you, you're about to store a list here."
Other than that, Python won't actually error out there.
Another example purpose:
You assign the result of a function that _declares_ it will return a list of floats
def some_func() -> list[float]:
...
rslt_list = some_func()
Then you do this:
print(", ".join(rslt_list))
The IDE will warn you that the str.join() function requires a list of str, but you're calling it with a list of floats.
In this case, if you don't heed the warning, your program will raise an error at that point (because of .join()'s requirement).
Again, in all case, you're only given a hint that _probably_ something is not quite right. It still won't change Python into a statically-typed language. Just another tool to help a Python Programmer prevent errors due to Type Mismatch.
@@PanduPoluan bro! Thanks for the answer!! Super detailed!!
7:01 Bummed that you didn't mention that changing f to e gives you the number's scientific representation
This gave you a chance to look clever. Be grateful.
👍💯
In the first example, int variable n assigned a number in scientific notation returns a float number when printed, but no error occurred. In what sense must n be declared a float therefore?
It’s not a type declaration, it’s a type hint given as an annotation. Annotations in Python have no effect at run time so no error occurs. They are just hints to a static type checker.
Type annotations are just comments, and comments always lie.
You need to be careful with the equal sign formatting. It is relatively new. I sometimes have to use Python 3.7 because that’s what is preinstalled and there it does not work.
Python 3.7 has reached the end of its life in terms of support, nothing to be careful about, it's just time to upgrade :)
@@Indently we are using Amazon Linux 2 still where it is the default. As it is only for management stuff we use the python that is available and don't install a later one. We will migrate to AL 2023 (or newer) eventually.