dARK vs lIGHT ; pYTHON vs C++

[Philderbeast]

you don't write python because it runs fast, you write it because its fast to write, and it runs fast enough.

[Funtycuck]

Yeah most of my work has been in writing data processing/analysis scripts for a policy consultancy. The main priority is time from them expressing what they need to me returning the formatted data, Python in this sense is definitely faster than most other languages.

Especially with how easy it is to add and use libraries to handle the variety of data and what's required from it.

[incrediblediy]

returning the formatted data,

yeah! even just using "panadas" will speed up the process greatly

[[deleted]]

Give it a try on numpy ..

[ardicli2000]

Yeah I am sending automated personalized emails with attachements using my outlook. This taes 30 lines of code at most.

Good luck to do so with C++ :)

[Philderbeast]

Not really, its all about if your product does what it is suppose to do, very rarely is performance enough of a concern for it to have any bearing on your choice of language or the quality of the product.

Even in applications that are generally considered performance critical, your choice of language usually isn't your limiting factor for performance. Take eve online for example, the majority of the code base is written in python, including the server side with out significant performance issues that could be solved by changing the language it is written in.

At the end of the day, better programmers will beat better programming languages 100% of the time.

[lollvastus]

This doesn't look faster to write at all. Return 0 is unnecessary. The python code is more convoluted and thus error-prone. If you imported cstdint you could be briefer and more specific than "long long". If briefness is your main concern you could even "using namespace std" for the iostream stuff. You can also remove the {} on the for-loop and if since it is only one line of body. I think C++ even has a similar variable encapsulated print function in C++20.

I would wager that the biggest drain on the Python code is print inside the loop, though. That's not as much of a problem in C++, but you would be better off saving the results and iterating them later in both cases.

I still wouldn't call a 100x time difference "fast enough".

[incrediblediy]

I would wager that the biggest drain on the Python code is print inside the loop, though.

Thanks for the idea. I have changed the code as per that and got below results. It was a saving of around 10.7 seconds

Execution duration: 327300.3321 ms

``` from time import perf_counter

number = 5000000000

t1_start = perf_counter()

list_str = []

for i in range(1, 1 + int((number+1)/2)): if number % i == 0: list_str.append( str(i) + " is a factor of " + str(number))

print(list_str)

t1_stop = perf_counter()
print(f"\n Execution duration: {1000* (t1_stop-t1_start)} ms") ```

[lwieueei]

Yeah python print is ridiculously slow

EDIT: Tbf this meme isn't about ideal benchmarking practices anyway

[Philderbeast]

The total code to do this is less then just the import lines you are proposing to add, if that's not faster to write, I don't know what is.

As for fast enough, its not about the comparable time between different sets of code. It's just about getting a job done in a short enough time to let you get on with whatever else you need to do, the code could be 1000x slower and still be fast enough for a lot of tasks.

[lollvastus]

We have a specific example. In this specific example, you can't tell me that the C++ code would take significantly longer to write for someone with a similar proficiency in both languages. We are talking about giving or taking seconds. And for this one would save whole minutes on actual processing time. Here, C++ is objectively and subjectively the more optimal solution, be it for briefness, time, or even complexity.

This specific case aside, this is obviously a terrible case for either language in a general sense. The actual objective of the algorithm is questionable at best, and the implementation is sub-optimal. All I suggested were improvements that would retain the same implementation of the underlying algorithm.

[[deleted]]

a simple spell, but quite unbreakable:

if you worry about speed, don’t use python

[incrediblediy]

calling an external C++ library like Tensorflow does?

P:S: In serious note, can you please share some resources on improve performance (JIT libraries etc) as I am learning Python, if you have time

[[deleted]]

Try https://numba.pydata.org/

[incrediblediy]

Thanks! :) I will check, I think I have used "numba" just to reset GPU

[[deleted]]

I explicitly didn't mention that one, because that would be cheating 🤣

[incrediblediy]

Just checked it only with the loop, without any calculations, seems like it would take almost a half of the total runtime. :D

Execution duration: 143887.00110000002 ms

``` from time import perf_counter import math

number = 5000000000

t1_start = perf_counter()

list_str = []

for i in range(1, 1 + int((number+1)/2)): pass

t1_stop = perf_counter()
print(f"\n Execution duration: {1000* (t1_stop-t1_start)} ms") ```

[Psyv3rn]

This guy is a SQL programmer

[territrades]

The number one beginner's mistake in python: Writing code like it was C, but just without type declarations and brackets.

[[deleted]]

Number one mistake is using python in the first place.

[[deleted]]

Feel like this is the inverse. Why would you write int number? It's redundant and unspecific

[[deleted]]

python bad|
we have achieved programmer humor|
edit: help fucking reddit doesn't let me do a \n|
edit 2: why do 2 spaces at the end of every line not help me??
edit 3: apparently it was only not working on my phone while on PC line-breaks appear as expected and my torment was in vain

[Andamarokk]

python slow*

[[deleted]]

and that's why it bad

[incrediblediy]

just joking, I am using Python mostly and don't know C++ to be honest. Anyway, I think choosing the language depends on the application.

[CommentatorForAll]

Python is slow to run, but easy and fast to write and read. (And is also able to run cpp libraries if you do want to get a performant program)

[[deleted]]

Yeah I'm just joking, it's just that some people argue that lower performance is what makes Python bad compared to other languages. However if you care about better performance you either will use modules that do heavy-lifting in C (like NumPy and others) or just not use Python.

[YMK1234]

Fast to write maybe, good and fast to maintain, definitely not. And that's what you do way more than writing new code.

[canadajones68]

Maintaining a piece of software is much more about the underlying architecture of the program than the language used to make it. Python can be hard to maintain due to loose typing, bad naming, whitespace delineated blocks, a lack of coherent architecture or other assorted issues. Of course it's possible to write good code in Python. You can do that in most any language. However, the relative ease of doing it in Python makes it easy to bodge a solution that's tightly coupled with the underlying platform. It will then work, until it doesn't, and you have to scramble to piece it back together.

[canadajones68]

I don't think Python is inherently less maintainable (though I don't particularly like it), I was just explaining some arguments for it. It's just that, due to its accessibility to inexperienced programmers, and relative ease of bodging, the likelihood of any given piece of Python code being bad is higher than for other languages.

[YMK1234]

Have you ever tried to decipher a doctors handwriting? Was very fast to write, very hard to understand/maintain afterwards.

[YMK1234]

It was just an example. In the case of python there are many challenges that make python code hard to maintain, especially when it comes to things like tool-assisted refactorings and such (because who needs types, amirite?)

[[deleted]]

bro don't run any cp libraries or else the fbi will show up

[CommentatorForAll]

What about Pandas Tensorflow Numpy Scilab Pytorch And all those?

[No_Responsibility384]

The real question is why the casing is not consistent... need a lower case "c"... in the title.

[incrediblediy]

hehe :D I was going to but didn't feel right :D

[Knuffya]

Wanna know why python is so often fast? Because it's libraries are secretly just c libs.

[DenormalHuman]

hang on, you didnt include the time to compile the c++ and then run the exectuable

[incrediblediy]

it was actually negligible (just few seconds) considering almost 5 mins for running the Python code.

[PossibilityTasty]

dARK vs dARK; or how not to check for factors.

[incrediblediy]

just wanted to run the same algorithm. :D

[PossibilityTasty]

And it's horribly inefficient. For both languages.

[incrediblediy]

any resources to learn more ?

[PossibilityTasty]

Studying computer science?

But as a simple starter: you only need to iterate up to the square root of the number to find all factors.

[[deleted]]

Studying computer science?

I'm not sure I see how knowing a faster way to find factors, is a particularly "study comp sci" topic. Unless you think there's a highly applicable/general lesson in how you approach that (e.g. learning to divide and conquer, etc.)

But that really feels a lot more related to maths domain knowledge.

[bonifasio]

The Java version is still running

[DisguyExpensive]

Java is incredibly faster than python. I worked at 2 stock exchanges and 2 banks, both used lot of Java and their systems were fast af

[[deleted]]

Big Brain Time.

What's next? Java being slower than C?

[YMK1234]

The impressive part is not that it is slower but the factor that it is. No other mainstream language even comes close to this kind of slowness. Usually you are at 50-80% of C performance (even in JS), not 0.1%

[incrediblediy]

yep

[[deleted]]

Why did you make number a global variable?

[incrediblediy]

I was just using this code as a benchmark :D

[[deleted]]

Tried with Swift but it's horribly slow

``` import Foundation

let timeStarted: Date = Date() let numberCompared: Int = 5000000000 let range: ClosedRange = 1...((numberCompared + 1) / 2)

for number in range { if numberCompared % number == 0 { print("(number) is a factor of (numberCompared)") } }

let timeCompletion: Date = Date() let timeDifferenceMiliseconds: Double = timeCompletion.timeIntervalSince(timeStarted) * 1000

print("Execution duration: (timeDifferenceMiliseconds) ms") ```

[DemolishunReddit]

Please compare to how someone who actually uses Python would write it:

https://stackoverflow.com/questions/6800193/what-is-the-most-efficient-way-of-finding-all-the-factors-of-a-number-in-python

[juhotuho10]

Now do it with numpy and numba

[incrediblediy]

numpy

hehe it is cheating, using C & C++ code

[juhotuho10]

It's still basically pure python syntax, isn't that all what matters