Vivian Darkbloom posted:

I'm finding how hard it is to make a cross-platform console interface that isn't horrible for a little strategy game project, so it's time to get a basic GUI framework set up. I just read the Python Wiki page on GUI programming and I am looking at pyjs as a possibility, since targeting web browsers might be easier than rolling my own GUI entirely. Not sure, though -- ideally I'd like something that's programmer-friendly and doesn't require a lot of setup for a user running my program. Any recommendations on what might be the best GUI choice?

Hughmoris posted:

For those that work with Excel, what Python library do you use?

Boris Galerkin posted:

My first instinct was that conda isn't in your $PATH or whatever the Windows equivalent is, but I just popped open a PowerShell (I don't have conda installed on this computer) and typed 'conda list' and it complained to me about conda not being a recognized command. So unless you trimmed that out of your post then I dunno.

By the way I think PyCharm is the best thing ever as well, coming from vim for approximately 10 years now (gently caress I'm old). I just started using it though and yeah I could definitely see where it might be confusing and intimidating.

baka kaba posted:

One day you'll reach a point where all the Google results are for 3.x docs no you won't

Cingulate posted:

I think I need async/await ..? But I have never used either, nor understood the descriptions.

I am training a neural network on synthetic data, and I'm alternating data generation and training. So it looks like this:

code:

for epochs in range(number_of_epochs):
    X, y = generate_data(10000)  # generate training data
    model.train(X, y)  # train the model for one epoch

Now the data generation actually takes a significant fraction of the time it takes to train the model on the generated data (about 30%). But both run only on 1 CPU core (the model runs on the GPU). So it would save me some time if I could generate the next batch of data while the model is training. I.e., if I could do something like:

code:

X, y = generate_data(10000)  # generate training data
for epochs in range(number_of_epochs):
    model_finished = without_GIL(model.train(X, y))  # start training and release GIL
    if epochs < number_of_epochs:  # don't need for last epoch
        X, y = generate_data(10000)  # use CPU while model is running on GPU
        wait_for(model_finished)  # only proceed to next iteration once both training and data generation have finished

Is that something I could use await for?

Edit: both functions fully occupy 1 core. I think that means await is not enough? Maybe I should just abuse joblib heavily, that I could do.
Double Edit: joblib uses pickling and the model is compiled and sent to the GPU, so I think joblib wouldn't work.

VikingofRock posted:

So I've been doing more python lately, and while I feel like I have a decent grasp on the language itself, I struggle with a lot of the idioms for structuring a program. For example, how should I layout the directory structure of my program, what is __init__.py, where do I list my dependencies, stuff like that. Does anyone have a good resource for learning that sort of stuff? Like the things that are necessary to use python effectively, but which are outside of the scope of the language itself.

edit: I often don't really know what various tools are, either, which falls into the same category. Like what is virtualenv / venv / pyvenv, etc? Is there a standard python code formatter? What other tools should I know about?

Hughmoris posted:

Are there any recommended articles/tutorials/blogs on working with sqlite in Python? I've just started learning a little bit about SQL and I'm trying to find best practices when incorporating it into a script.

I'd like to use it in a small script that parses an RSS feed and, if it's a new entry, inserts it into the DB.

Boris Galerkin posted:

Well I just had a frustrating time figuring out what was wrong with a part of my code when it turns out it was numpy being weird.

So I have a numpy array where some values are inf and some values are nan. I create a Boolean list of where these values in the array are inf/nan, and then I use these indices to do something to another array.

Like so:

code:

import numpy as np

a = np.array([1, np.sqrt(-1), np.nan, np.inf])  # [1, nan, nan, inf]

print(a == np.inf)
# F, F, F, T, as expected

print(a == np.nan)
# F, F, F, F, which is wrong

print(np.isnan(a))
# F, T, T, F

Is there a reason it does this? Does np.nan has an actual numerical value or something? I would have thought it would be treated in the same way as None where it just "is" or "isn't."

Boris Galerkin posted:

Is it ok to do this?

code:

class Foo:
    def __init__(self, parameters):
        self.parameters = parameters

    def __getattr__(self, key):
        try:
            return self.__dict__['_' + key]

        except KeyError:
            value = bar(self.parameters[key])
            setattr(self, '_' + key, value)
            return getattr(self, key)

parameters would be a dict, and bar() would do some calculations that only need to be done once and can be reused, but I might not always need said value. So my intention was to just evaluate and cache it iff I needed to.

I'm just not really sure if it's ok to use the __dict__ attribute like I am, and if I'm using __getattr__ properly.

Loezi posted:

Is there some reason @lru_cache doesn't work?

Eela6 posted:

I completely forgot about singledispatch. I don't think I've ever used it, but maybe I should have.

duck monster posted:

Ok, so I have a bit of a puzzle.

I've been loving about with Unreal Engine and I found this very fun bit of library: https://github.com/20tab/UnrealEnginePython I've been coding in C++ on this thing but honestly I'm a bit poo poo at C++, something about that loving language just gives me the hebeejebees. If it was C, no probs, but something about C++ just pisses me off. Anyway , this library is awesome. it works, you get the GPU crushing sexiness of UE4, but you can script the *poo poo* out of it with Python. Theres bit of a focus on editor automation, which is fine (Makes pulling 3d-coat textures together into proper materials much saner). But it also seems to work pretty well with in game scripting because it has some magic introspection auto api generating poo poo. I strongly recomend playing with this, if you fancy making games, because it turns UE4 into the first AAA quality python engine.

Anyway, heres the problem. UE4 uses an object/component model. Each item in the game (and light, and camera and sound and whatever) is an Actor object, and has a list of components attached, with the basic idea that you build up your objects by composition of components. Its kind of the gold-standard pattern in game dev. So the UE4 python plugin lets you use a python class as a component.

The life cycle of the thing is that when the Actor is instantiated., the PythonComponent instantiates the class ,then at some point , very soon after, all the components (C++, Python, etc) have a begin_play (or BeginPlay in the C++ classes) method which acts as the setup function when the scene starts winding into action. Of course like any python class the __init__ is called at true instantiation, but this is not really when one should construct as the UE4 python plugin appears to wait till AFTER __init__ to add the bits and pieces to the class to let it behave like a real UE4 object.

Anyway, I want to have a component called "Transmitter" that acts as a relay to a python server via rabbitMQ. The other objects in the game need to register with it using a register method. All good and easy, and I need to grab a reference to that transmitter so the registration can take place. Normally I'd just use a Singleton but my usual method of making a singleton in python involves the rest of the program agreeing not to call __init__() and instead using a static method that grabs an instance and everything else agrees to behave itself.

The problem is __init__ is called by the UE4 framework, and I have no control over the order of things being instantiated and I am not entirely sure I can be sure the BeginPlay on the objects wanting to register before the Transmitter has done its __init__.

So the question is, is it possible to code a Singleton that can if necessary transmogrify its own instance into an existing instance if snarfed via __init__()

Seventh Arrow posted:

I'm looking for a python tutor and not really sure how to go about it. I'm taking a data science course and my lack of proficiency with python is my biggest weakness. So obviously I want to focus on data science/data analysis concepts, but also not-quite-so-directly related things like web scraping and working with APIs.

I've read "Python Crash Course" and "Automate the Boring Stuff with Python" so I'm familiar with the basics but I tend to struggle with coming up with code on my own, or analyzing existing scripts.

I live in Toronto, but this seems like the kind of thing that could be done via skype or discord or whatever. I guess(?)

The catch is that I'm unemployed and receiving employment insurance, so I don't have a lot of cash to throw around. I'll try to work out something reasonable, regardless.

Boris Galerkin posted:

I don't have internet access on some of these machines.

Seventh Arrow posted:

Thanks for the suggestion. If I do "python meetup_data.py > meetup_data.csv", I just get a blank file. I think what you might be trying to do is pull "data" groups from the API, but the API only has a category for "tech." It's necessary - at least, as far as I can tell - to further filter the results from there.

If I try doing "python3 meetup_data.py > meetup_data.csv", then I get the error:

File "meetup_data.py", line 32
continue
^
TabError: inconsistent use of tabs and spaces in indentation

Which is strange, since the formatting of the indentation seems to be consistent: https://pastebin.com/aHvT5GfM

Linear Zoetrope posted:

What's the best tool for documenting Python 3 for an open source project (there are multiple languages in this project, but let's assume I'm gluing together the docs from different languages manually)? It looks like there are several options, and I'm not familiar enough with the Python open source world to know what's standard. I feel like I rarely see the builtin PyDoc, and see sphinx referenced more often, but I don't really know the tradeoffs and pros/cons of all the various tools.

creatine posted:

Wondering if something like this exists in Python.

I have some data that gets analyzed and then put on a scatter plot. I was using matplotlib and bokeh but I've got a lot of data and multiple datasets on the same graph and was wondering if there was a module or way to save scatter plots into PSD or some other layered image type that I can use to edit.

outlier posted:

So if I was looking to make a "fast" version of some Python code (in the sense of writing the details in some lower-level language but keeping the API the same like cStringIO versus StringIO), what's the best way to go around it. Is it still using C? Use a helper library like Pyrex or Cython or Boost? Is all that Rust and Julia stuff viable?

Cingulate posted:

"The Python default for dealing with tabular data."

Or, for people who know R: "Dataframes for Python."

Seventh Arrow posted:

I have a comma-separated spreadsheet with a bunch of information about condos in my city, most importantly it has the latitude and longitude of these places. I want to be able to output these coordinates onto google maps but I'm not sure how to go about doing this. I looked at this link but none of the API's seem to quite provide what I'm looking for (at least, not with python). Any suggestions?

Seventh Arrow posted:

I need to put markers on a map, but since this is for a data science python course I need to find a ~*pythonic*~ way of doing it. The module that was linked to earlier was good, but I need to find around some of the details.

Slimchandi posted:

Portland Sucks posted:

Got it, I guess this is pretty much how I was attempting to write my tests. I figured that Excel likely had precision loss in it as well and I know the guy who originally wrote the Excel workbook we're using put no thought into what he was doing regarding precision. I just want to make sure that what I'm producing isn't going to be wildly off the mark.

Mrenda posted:

Is there a particular setup I should have for developing with Python on windows?

SurgicalOntologist posted:

I'm doing a bunch of computations and saving them to a database. The following function is supposed to be committing to the database every 100 results (based on the variable commit_interval), and stopping after 10,000 (the value of total). But I'm not getting 10,000 results on each backtest_set, instead I'm getting 9,900. Can anyone spot the error? Am I making a basic off-by-one -ish mistake or do I have some weird race condition? I can't figure it out. Here's the code.

Python code:

    results = []
    for i, result in enumerate(tqdm(
            backtest_set.run(),
            unit='entry', desc='Backtesting', total=total, unit_scale=True,
    ), 1):
        results.append(dict(backtest_id=backtest_set.id, fantasy_points_hundredths=result))
        if not i % commit_interval or i == total:
            db.execute(models.BacktestResult.__table__.insert(), results)
            db.commit()
            results = []
        if i == total:
            break

Any ideas?

The actual work is here is done inside the generator function backtest_set.run(). And if you haven't seen it before, tqmd is just a progress bar library (a pretty great one), as I'm using it just wraps an iterable. The only other things there are my models and sqlalchemy session db.

unpacked robinhood posted:

I'd like to "live-update" a geographical map with rectangular overlays, as soon as background processes bring up fresh data.
So far I have an ugly blocking thing in matplotlib/cartopy that requires manually closing the window to resume processing, until updated content pops up in a new window.
Can I make a non blocking display in matplotlib, or is there something more suitable out there ? I've seen a few SO posts on the issue but the solutions looked super clunky and confusing.

Protocol7 posted:

So what's the deal with multithreading in Qt?

I basically have a long-running background task, that logs through a logger, and I want to capture the logging output and have it stream to a QTextEdit.

It sort of works, except that the main UI thread still gets destroyed and freezes up. In my research I came to the conclusion that the correct way to do it is with a QThread and a QTimer to periodically stream data from the StringIO that I have the log redirecting to, but I'm clearly doing something wrong.

I know that the logging redirection works since it no longer shows up in the standard output window of PyCharm, but my UI thread just freezes so I don't see the QTextEdit ever updating (and I have to force-quit python...).

Nvm, I guess I was using StringIO wrong. I ended up just redirecting the output to an actual file (which will come in handy when we need to debug) and that works for whatever reason.

QuarkJets posted:

The general rule is that Python will not create a copy unless asked. Since you expect the output list to have all of the elements of the input list, except modified, you can copy it at the start of the function and then modify the elements in place.

Python code:

completed = list(input_list) 
for entry in completed:
    # do something to entry
print(completed) 

Hughmoris posted:

Anyone ever futz with extending Python using C or Rust to gain performance?

I've been reading some articles on it and the idea seems intriguing but I'm sure the reality can be a headache.

SirPablo posted:

Not sure that is quite what I'm aiming at. He's an example of one polygon that is rasterized at 0.01°x0.01°. I'd like to do this for hundreds of similar polygons, but the step I'm scratching my head on is counting them up grid by grid on a much larger domain, thus giving me a polygon density.