Python Discoveries
Here, whenever I will remember, I will be writing what I have discovered about Python when creating one project or the other.
Functionalities that took me a long time to discover and when I finally did - it helped me a lot.
First of all I don't want to forget about these functions, second of all - I would like to share them with you.
1 Scope
You can assign a returned value from functions to a variable
I was returning a value from function, wanted to use it another function. I had to assign the returned value to a function first and only then I could use it. SCOPE is the important word here.
Thanks to Karina
2 f"" string > templates
Qrcode pkc
I had to recreate a QR code template that is created with batch to a program in python(more controls, better gui, etc).
So I have chosen something like this for this task. Had a massive
template with certain strings that had to be replaced. All is good,
managed to make it work, but whenever I would have a: 9999$A99999
my
delimiter and value that $A surrounded with other symbols - the
delimiter would not be replaced with what I have described.
f"99999{A}99999"
has no problem doing that, this is why I have chosen
it for this project.
3 flask dispachermiddleware
4 Python set()
The set() function creates a set. No repeating values.
list_numbers = [1,2,3,4,2,5,5,1] # create set from list numbers_set = set(list_numbers) print(numbers_set)
Useful when I wanted to extract all authors in a list ONCE.
Amazing, thanks to Karina.
![discoveries3.png](./media/discoveries3.png)
5 listdir vs chdir
This one confused me. I ran a for loop similar to this:
x = ./Dropbox dir = os.listdir(x) print(dir) for file in dir: # do this and that
and I kept wondering why my for loops runs IN THE directory where this script is placed(I printed it out, it knows the dir I want) and not in the directory that I specified in x.
Now it seems obvious, but I simply should have changed the director to the specified one before running the for loop.
something similar to this:
for file in os.listdir(os.chdir(x)):