What's one cool feature in Python 3 that you've learned about recently and feel that others would benefit from knowing too?

Answer 1

Thoq! I actually recently made a code explaining the difference between += and append()

https://code.sololearn.com/cwIQwwnM8NjA/?ref=app

Answer 2

Thomas Williams Yes, I profoundly dig list comprehensions! Did you know there are dictionary comprehensions too?

https://code.sololearn.com/cK7uik9C53a7

Answer 3

I also just discovered that "try-except" lines can't catch a SyntaxError. Why? Because they catch EXCEPTIONS and SyntaxError is not an exception (like, e.g. EOFError or NameError), it's a, well, a syntax error.

A code with a syntax error won't run. This means the "try-except" lines never run either.

Answer 4

Well, I recently learned that var += 1 is not necessarily the same as var = var + 1 if you use it with mutable values. So using += with lists behaves like append whereas List = List + whatever is a brand new assignment.

And also there will be a major change in Python 3.8 giving us the highly controversial assignment expressions using a socalled walrus operator: :=

This gives you the possibility to assign a name to a value inside an expression like this:

while endCondition:= determineEndCondition():

Here endCondition is assigned the result of determineEndCondition() on each iteration and the while-loop keeps running until endCondition isn't False or None etc.

Answer 5

It finally sank in that in comprehensions with conditions,

'if' goes AFTER 'for' but 'if-else' goes BEFORE 'for'

https://code.sololearn.com/cUYk1EkgmVyf

Answer 6

How to create your own python module

https://code.sololearn.com/cNW7BiRF0ELJ/?ref=app

Answer 7

Thoq! After 10 minutes of research on the walrus operator, I'm still at a loss as to how it works. 😁 Probably need to skill up a bit.

Answer 8

Sry, should have explained more. Knowing how to add lists is important for recursive programming. So when doing a graph search you can use append or += for mutating a list in global or an upper scope to "store" results (like a path that lead to a specific node). But to find such paths in the first place to you need a new assignment in each function scope giving each scope its own current version of the path. Hope that makes sense.

Answer 9

I totally understand. I am not trying to avoid it but I usually prefer the iterative approach.

Answer 10

Nice. I learned it the hard way while writing a dfs (the recursive version).

Answer 11

Well list comprehensions have been around for a while now, but only recently have I started using them. Now I use them all the time in my applications. Check it out

https://code.sololearn.com/ccaEkQ35qJGV/?ref=app
https://code.sololearn.com/chu0Xaheiq4W/?ref=app
https://code.sololearn.com/cr2bE8cvDCSN/?ref=app
https://code.sololearn.com/c91RSRAdroXg/?ref=app
https://code.sololearn.com/cB5nLaMs0HrK/?ref=app
https://code.sololearn.com/cZ0ljNOI3SOq/?ref=app

These were all done in a time period of about 2 days after I discovered it😅

Answer 12

F_strings

https://code.sololearn.com/cWUjwDVLAfAE/?ref=app

Answer 13

Tuples (Immutable lists) 🙄

Answer 14

Another one I just discovered and will be using for more complex projects with many functions/variables:

type hinting

Especially useful if working on a team as it makes code more readable

A simple example here:
https://code.sololearn.com/ch58CLulWJcQ/#py

Answer 15

Yep. I used set comprehensions too, one of these codes needed one but I cant remember which😅

Edit: it was the pattern solver. To get the second difference I needed unique values. If there was more than one value in there, then it wasnt a pattern or the program cant solve it

Another one was the Vowel and Consonants one. I wanted unique values for each letter

Answer 16

Thomas Williams Nice, I didn't know about set comprehensions.

Answer 17

David Ashton Great point! I always end up googling it every time I need an if-else condition in a list comprehension. Hopefully it will stick this time!

Answer 18

# unpacking [*] vs list()

[*filter(lambda x: x.isalpha, "ab1")]

Answer 19

S-Stefanova, they are really great if you want unique values for each item. Check the pattern solver and the vowels one and see if you can spot them🔎

Answer 20

Thomas Williams Depth First Search (had to google it)