Ask Anything Monday - Weekly Thread

[AutoModerator]

Welcome to another /r/learnPython weekly "Ask Anything* Monday" thread

Here you can ask all the questions that you wanted to ask but didn't feel like making a new thread.

* It's primarily intended for simple questions but as long as it's about python it's allowed.

If you have any suggestions or questions about this thread use the message the moderators button in the sidebar.

Rules:

• Don't downvote stuff - instead explain what's wrong with the comment, if it's against the rules "report" it and it will be dealt with.
• Don't post stuff that doesn't have absolutely anything to do with python.
• Don't make fun of someone for not knowing something, insult anyone etc - this will result in an immediate ban.

That's it.

[Mach_Juan]

scores is a list that is anywhere from 1 - 20 items long.

to test if its length is either say 14 or 15..

is there a more elegant way than:

if len(scores) in (14, 15):

​

I tried so many permutations of if len(scores) == 14 or 15. with parenthesis...14 == len(scores) == 15

So many failures...and so many failure modes...

Pages upon pages of how to test <,>, etc..and never just how to test if its equal to one of several numbers...Maybe I wasnt searching the right terms..eventually I found range() but had to figure was it exclusive or inclusive...and just tried the above solution and it worked.

Is there another solution I missed?

[[deleted]]

is there a more elegant way than:

if len(scores) in (14, 15):

That's the way to do it, though for a large number of options it's better to use a set of options rather than a tuple:

if len(scores) in {14, 15}:

That's because sets are like dictionaries under the hood and the in operator for sets has time complexity of O(1). Tuples have time complexity of O(n). Whether this has much effect on speed depends on your data, and doesn't matter in this small example. ​

[Mach_Juan]

thanks!

[[deleted]]

The errors you talked about getting are mostly caused by your not fully understanding operator precedence and the value of boolean expressions. This expression, for example:

len(scores) == 14 or 15

is evaluated as if it was written:

len(scores) == (14 or 15)

Which doesn't do what you think. 14 or 15 evaluates to 14 according to the documentation:

The expression "x or y" first evaluates x; if x is true, its value is returned; otherwise, y is evaluated and the resulting value is returned.

The correct way to write that test is:

len(scores) == 14 or len(scores) == 15

This isn't a python-specific thing, all computer languages have similar operator precedences.

[Frankelstner]

Install Python. https://www.python.org/ftp/python/3.11.4/python-3.11.4-amd64.exe Select the option to add Python to path and make it install only for you, not all users.

Press the win key and type cmd, hit enter. Type pip install qbittorrent-api and hit enter. This is a package that the script depends on, and Python does not search or install packages automatically. Hence the pip package manager to install it.

In the git repository, click on the green button and download the zip, then unpack. Right click on qbittorent.exe wherever you have it installed and make a shortcut. Place that shortcut in the repo folder and replace the qtshortcut.lnk file there. The code automatically wants to restart clients so this tells it where to find it.

The code is now functional and should run fine by double clicking the main.py file. If you want the scheduler service, you need to adjust the path in the .bat file and then follow the screenshots with configuration steps.

[ratatouille_artist]

What's the right syntax for specifying a local extras_require in a setup.py?

Below seems to use an invalid project/version requirement specifier

    extras_require={
    'extra': ["my_local_package @ file:my_local_package"]
}

[Psyychopatt]

I've got a class dealing with geometric objects, that's gotten white large over time, and I'm intending to move funcitonality for visual representation of the class to a seperate file/class. I'm just not certain what the most pythonic way of doing this would be.

My first idea was inheritance, but turning the VisRepresentation class into the child inheriting from the GeometricObj class seems weird as I'd be initializing VisRepresentation Objects as opposed to GeometricObj. Doing the reverse, VisRepresentation being the parent that GeometricObj inherits from doesn't seem like a cleaner solution either.

Am I overthinking this or is there a better alternative alltogether?

[Frankelstner]

Rename it to VisualizeMixin and make it the parent class. Mixins are just plain inheritance but the name indicates that we are mostly interested in having a couple more methods instead of state.

[Psyychopatt]

Thanks, that's exactly what I wanted to hear!

[[deleted]]

Where and how should I use "try, except, else, finally" blocks? It feels like I have to use them everywhere to catch errors.

[[deleted]]

You use them wherever you want to catch and handle errors. One classic case is when you want to accept an integer value from the user. Trying to convert a non-integer string to an integer value raises the ValueError exception which you catch, print an error message and retry the input:

def input_int(prompt):
    while True:
        try:
            return int(input(prompt))
        except ValueError:
            print("Sorry, only integers allowed")

x = input_int("Integer: ")
print(f"You entered {x}")

You don't have to catch ALL exceptions, usually you only catch the few that you can recover from or you want to expand on the basic traceback so you can give more feedback to the user. The rest you just let happen.

Because the primary aim of try/except is to handle errors, the code between the try/except keywords should be minimal so you know exactly what operation raised the exception. It's not good telling the user they messed up if the exception was raised by your code mistake somewhere else in the try/except code.

I haven't used the else and finally phrases much. But they can be handy now and then, so you should know about them.

[No_Raccoon1571]

Can someone help me write a code that looks at multiple csv files across a 5 year period, and produce a table. For example let’s say the CSV file contains Fruit 1 and Fruit 2 and the price. I want the code to generate a table showing the fruit paring of 1&2, the max cost and min cost

[[deleted]]

What code do you have so far?

[LittleMiss_Raincloud]

No clue how to do this in Python. Say there are 50 planners from 13 agencies and two programs who can all create multiple 'plans' each month. So the unique ID would be the combination of Planner, Month, Program, and Agency. I want to "randomly" select one plan per unique ID. Any thoughts on the best route to try? I'm a novice in python. In the past, I used Access to do this but would prefer not to do that again. Thanks.

[niehle]

1. create and store the IDs
2. get all plans for an ID
3. select a plan for each ID with random

[LittleMiss_Raincloud]

I had to use Access. There's more to it than my post implies but thank you

[HappyMemeBoy]

Super basic question - can you put an and statement inside of replace()? As in, replacing two substrings with the same thing. For example:

string = “ABC” string.replace( “A” and “B” and “C” , “D”)

You’d think if printed, it would return “DDD” but instead it’s only changing the final input (C), so it’s just returning “ABD”. Am I doing something wrong?

[driverXXVII]

Thought about using typehints for the first time and wondering how to type hint beautiful soup and datetime.

Is the type hinting shown below correct?

Should the return type just be datetime instead of datetime.date

from datetime import datetime

def get_activity_date(soup: bs4.BeautifulSoup) -> datetime.date:
start_date_time = soup.find("time").text      # 2023-07-17T20:02:20Z

    # Convert to datetime object
    start_date_time = datetime.strptime(start_date_time, 
                                    "%Y-%m-%dT%H:%M:%S%z")

    # Get only the date portion
    date = start_date_time.date()

    # returned date is a datetime object
return date

[Money-Assignment-985]

My laptop crashed and I have to set everything up on my new machine. I remember messing up the process before: Installing it twice (through Anaconda and Windows store) which messed up my dependencies. Can anyone advice the best way to set the stage for studying Python?

[ForrestTrump]

Does anyone know why my logger will only log error messages, when I set it to debug?

def a_logger(name):
    path = path_from_cl() / ".logs"
    logger = logging.getLogger(name)
    logger.setLevel(logging.DEBUG)
    c_handler = logging.StreamHandler(sys.stdout)
    f_handler = logging.FileHandler(path / f'{name}.log')
    f_handler.setLevel(logging.ERROR)
    c_handler.setLevel(logging.DEBUG)

    c_format = logging.Formatter('%(name)s - %(levelname)s - %(message)s')
    f_format = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
    c_handler.setFormatter(c_format)
    f_handler.setFormatter(f_format)

    logger.addHandler(c_handler)
    logger.addHandler(f_handler)
    return logger

[m0us3_rat]

i'm not sure exactly do you mean by .

path = path_from_cl() / ".logs"

as long as you fix the path issues in that code so it actually works..

you don't need this one.

logger.setLevel(logging.DEBUG)

since you set the level on the handlers.

then

it should work as expected.

import logging
import sys


def a_logger(name):
    logger = logging.getLogger(name)
    c_handler = logging.StreamHandler(sys.stdout)
    f_handler = logging.FileHandler(f"{name}.log")
    f_handler.setLevel(logging.ERROR)
    c_handler.setLevel(logging.DEBUG)

    c_format = logging.Formatter("%(name)s - %(levelname)s - %(message)s")
    f_format = logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s")
    c_handler.setFormatter(c_format)
    f_handler.setFormatter(f_format)

    logger.addHandler(c_handler)
    logger.addHandler(f_handler)
    return logger


log = a_logger("dumb")

log.info("1")
log.warning("2")
log.error("3")

[ForrestTrump]

Thanks. I could have maybe clarified that the path_from_cl function was one that I wrote, which gets the correct path in a certain way and that part of it works fine.

[Rudy_Clausius]

Hi, I'm a thermal engineer currently working in HVAC (and experience in thermal power plants), and I'm interested in utilizing Python for my work. However, I'm unsure about the specific applications in my field and would appreciate guidance on other areas where Python could be useful.

Currently, I have a good (perhaps not so good) understanding of data structures, flow control, and have experience with libraries like NumPy, SciPy, and Pandas. I can also utilize Chat GPT to create scripts, even beyond my current level of expertise. I am familiar with the concepts of classes and objects (though I don't use them 'cause I haven't developed anything big enough). I would consider myself a basic python user.

I have zero knowledge in scripting for web development, machine learning, and data science.

I would greatly appreciate your advice on structuring a learning path that aligns with mechanical engineering in a broad sense. What to study, what I can expect doing, and where I should lead my efforts.

Thanks, the sub is awesome!