Hey there!
I'm a chemical physicist who has been using python (as well as matlab and R) for a lot of different tasks over the last ~10 years, mostly for data analysis but also to automate certain tasks. I am almost completely self-taught, and though I have gotten help and tips from professors throughout the completion of my degrees, I have never really been educated in best practices when it comes to coding.
I have some friends who work as developers but have a similar academic background as I do, and through them I have become painfully aware of how bad my code is. When I write code, it simply needs to do the thing, conventions be damned. I do try to read up on the "right" way to do things, but the holes in my knowledge become pretty apparent pretty quickly.
For example, I have never written a class and I wouldn't know why or where to start (something to do with the init method, right?). I mostly just write functions and scripts that perform the tasks that I need, plus some work with jupyter notebooks from time to time. I only recently got started with git and uploading my projects to github, just as a way to try to teach myself the workflow.
So, I would like to learn to be better. Can anyone recommend good resources for learning programming, but perhaps that are aimed at people who already know a language? It'd be nice to find a guide that assumes you already know more than a beginner. Any help would be appreciated.
Honestly? No. The best resource is you. Ask questions. Get experience. Ask questions. Get experience. Repeat.
It's not enough to learn. You also have to do. And you really should learn by doing in this field.
First of all - fuck Python. I'm sure it's possible to write good code in that language, but it's not easy and it requires a lot of discipline. I don't mean to be mean to Python, it's a truly wonderful language, arguably one of the best languages, when used properly. But it sounds like you're not using it properly.
Pick a language that:
Static typing forces you to have more structure in your code. You can have that structure in a dynamic language but nobody ever does in practice and part of the reason is all of the libraries and third party code you interact assume you have dynamic typing as a crutch to quickly and easily solve hard to solve problems.
It's far better to actually solve those problems, rather than avoid them. You'll tend to create code where bugs are caught when you write the code instead of when someone else executes the code. That "you vs someone else" distinction is a MASSIVE time saver in practice. It took me about 20 years, but I have learned dynamic typing sucks. It's convenient, but it sucks.
For more info: https://hackernoon.com/i-finally-understand-static-vs-dynamic-typing-and-you-will-too-ad0c2bd0acc7
On garbage collection - it's a similar issue. It's really convenient to write code where "someone else" deals with all that memory management "garbage" for you but the reality is you should be thinking about memory when you write your code because, at it's heart, 99.999% of the code you write is in fact just moving memory around. Garbage collection is like "driving" a Tesla with autopilot active. You're not really driving at all. And you can do a better job if you grab that wheel and do it yourself.
I recommend starting with a manually memory managed language (like RUST) to learn how it works, and then from there you might try a language that does most of the work for you without completely taking it out of your hands (for example Swift, which has "automatic" memory management for common situations but it's not a garbage collector and in some edge cases you need to step in and take over... a bit like cruise control in a car if we're going to use that analogy.
It's getting harder these days to find a language that doesn't have garbage collection. The industry has gone decades thinking GC is a good idea and we just need one more fix, which we're working on, to fix that edge case where it fucks up... and then we find another edge case, and another, and another... it's a bit of a mess and entire papers have been written on the subject. But anyway some of the best and newest languages (Rust, Swift, etc) don't have Garbage Collection, which is nice (because writing code in C or Fortran sucks — I'm not recommending that).
That's enough for now. Just keep muddling about learning those languages first before trying to tackle bigger problems. Programming is a difficult task, just like a baby learns to sit up, then roll over, then crawl, then stand, then walk with assistance, then stumble around, then walk, then run, then ride a bicycle with three wheels, then a two wheel one with no pedals, then a bicycle with pedals, then a car after that...
You skipped all those steps and went straight to driving a car (with autopilot). To learn properly, you don't need to go all the way back to "sitting up and crawling", but you should maybe go back just a little bit. Figure out how to get code to run, at all, in a language like rust, get familiar with it.
After you've done that come back here and ask what's next. We can talk about SOLID, Test Driven Development, all the intricacies of project management in git, exceptions vs returning an error vs failing silently, and when to use third party code vs writing your own (phew boy that's a big one...).
But for now - just learn a lower level language. Programming is a bit like physics. You've got elements, and under that atoms, and under that... well I don't even know what's under that (you're the scientist not me). There are "layers" to programming and it's important to work at the right layer and it's also important to understand the layer below and above the one you're working at.
If Python is at layer x, then you really need to learn layer x-1 in order to be good at Python. You don't need to go all the way down - you can't go all the way down (how do magnets work?).