🌐 Mailman 3 August 2022 - Python-list - python.org

Re: Parallel(?) programming with python
by Andreas Croci Aug. 8, 2022

Aug. 8, 2022

Thanks for your reply. On 08.08.22 13:20, Stefan Ram wrote: > Yes, but this is difficult. If you ask this question here, > you might not be ready for this. Indeed. > > I haven't learned it yet myself, but nevertheless tried to > write a small example program quickly, which might still > contain errors because of my lack of education. > > import threading > import time > > def write_to_list( list, lock, event ): > for i in range( 10 ): > lock.acquire() > try: > list.append( i ) > finally: > lock.release() > event.set() > time.sleep( 3 ) > > def read_from_list( list, lock, event ): > while True: > event.wait() > print( "Waking up." ) > event.clear() > if len( list ): > print( "List contains " + str( list[ 0 ]) + "." ) > lock.acquire() > try: > del list[ 0 ] > finally: > lock.release() > else: > print( "List is empty." ) > > list = [] > lock = threading.Lock() > event = threading.Event() > threading.Thread( target=write_to_list, args=[ list, lock, event ]).start() > threading.Thread( target=read_from_list, args=[ list, lock, event ]).start() If I understand some things correctly, a "lock" would be something that, as the name says, locks, meaning prevents parts of the program from executing on the locked resource until ohter parts have finished doing their things and have released the lock. If this is correct, it's not exactly what I wanted, because this way "parts of the program" would not "keep doing their things, while other parts do other things on the same data". I'm in principle ok with locks, if it must be. What I fear is that the lock could last long and prevent the function that writes into the list from doing so every second. With an FFT on a list that contains a few bytes taken every second over one week time (604.800 samples), I believe it's very likely that the FFT function takes longer than a second to return. Then I would have to import all the data I have missed since the lock was aquired, which is doable, but I would like to avoid it if possible. > > In basketball, first you must learn to dribble and pass, > before you can begin to shoot. Sure. > > With certain reservations, texts that can be considered > to learn Python are: > > "Object-Oriented Programming in Python Documentation" - a PDF file, > Introduction to Programming Using Python - Y Daniel Liang (2013), > How to Think Like a Computer Scientist - Peter Wentworth (2012-08-12), > The Coder's Apprentice - Pieter Spronck (2016-09-21), and > Python Programming - John Zelle (2009). > Thank you for the list. I an currently taking a Udemy course and at the same time reading the tutorials on python.org. I hope I will some day come to any of the books you suggest (I'm doing this only in my spare time and it will take forever).

2 1

Re: Parallel(?) programming with python
by MRAB Aug. 8, 2022

Aug. 8, 2022

On 2022-08-08 12:20, Stefan Ram wrote: > Andreas Croci <andrea.croci(a)gmx.de> writes: >>Basically the question boils down to wether it is possible to have parts >>of a program (could be functions) that keep doing their job while other >>parts do something else on the same data, and what is the best way to do >>this. > > Yes, but this is difficult. If you ask this question here, > you might not be ready for this. > > I haven't learned it yet myself, but nevertheless tried to > write a small example program quickly, which might still > contain errors because of my lack of education. > > import threading > import time > > def write_to_list( list, lock, event ): > for i in range( 10 ): > lock.acquire() > try: > list.append( i ) > finally: > lock.release() > event.set() > time.sleep( 3 ) > > def read_from_list( list, lock, event ): > while True: > event.wait() > print( "Waking up." ) > event.clear() > if len( list ): > print( "List contains " + str( list[ 0 ]) + "." ) > lock.acquire() > try: > del list[ 0 ] > finally: > lock.release() > else: > print( "List is empty." ) > > list = [] > lock = threading.Lock() > event = threading.Event() > threading.Thread( target=write_to_list, args=[ list, lock, event ]).start() > threading.Thread( target=read_from_list, args=[ list, lock, event ]).start() > > In basketball, first you must learn to dribble and pass, > before you can begin to shoot. > > With certain reservations, texts that can be considered > to learn Python are: > > "Object-Oriented Programming in Python Documentation" - a PDF file, > Introduction to Programming Using Python - Y Daniel Liang (2013), > How to Think Like a Computer Scientist - Peter Wentworth (2012-08-12), > The Coder's Apprentice - Pieter Spronck (2016-09-21), and > Python Programming - John Zelle (2009). > When working with threads, you should use queues, not lists, because queues do their own locking and can wait for items to arrive, with a timeout, if desired: import queue import threading import time def write_to_item_queue(item_queue): for i in range(10): print("Put", i, "in queue.", flush=True) item_queue.put(i) time.sleep(3) # Using None to indicate that there's no more to come. item_queue.put(None) def read_from_item_queue(item_queue): while True: try: item = item_queue.get() except item_queue.Empty: print("Queue is empty; should've have got here!", flush=True) else: print("Queue contains " + str(item) + ".", flush=True) if item is None: # Using None to indicate that there's no more to come. break item_queue = queue.Queue() write_thread = threading.Thread(target=write_to_item_queue, args=[item_queue]) write_thread.start() read_thread = threading.Thread(target=read_from_item_queue, args=[item_queue]) read_thread.start() # Wait for the threads to finish. write_thread.join() read_thread.join() print("Finished.")

2 1

[RELEASE] Python 3.11 release candidate 1 (3.11.0rc1) is available
by Pablo Galindo Salgado Aug. 8, 2022

Aug. 8, 2022

Python 3.11.0 is almost ready. This release, 3.11.0rc1, is the penultimate release preview. You can get it here: ## This is the first release candidate of Python 3.11 https://www.python.org/downloads/release/python-3110rc1/ This release, **3.11.0rc1**, is the penultimate release preview. Entering the release candidate phase, only reviewed code changes which are clear bug fixes are allowed between this release candidate and the final release. The second candidate and the last planned release preview is currently planned for Monday, 2022-09-05 while the official release is planned for Monday, 2022-10-03. There will be no ABI changes from this point forward in the 3.11 series and the goal is that there will be as few code changes as possible. ## Call to action #### Core developers: all eyes on the docs now * Are all your changes properly documented? * Did you notice other changes you know of to have insufficient documentation? #### Community members We strongly encourage maintainers of third-party Python projects to prepare their projects for 3.11 compatibilities during this phase. As always, report any issues to [the Python bug tracker ](https://github.com/issues). Please keep in mind that this is a preview release and its use is **not** recommended for production environments. # Major new features of the 3.11 series, compared to 3.10 Some of the new major new features and changes in Python 3.11 are: ## General changes * [PEP 657](https://www.python.org/dev/peps/pep-0657/) -- Include Fine-Grained Error Locations in Tracebacks * [PEP 654](https://www.python.org/dev/peps/pep-0654/) -- Exception Groups and `except*` * [PEP 680](https://www.python.org/dev/peps/pep-0680/) -- tomllib: Support for Parsing TOML in the Standard Library * [gh-90908](https://github.com/python/cpython/issues/90908) -- Introduce task groups to asyncio * [gh-34627](https://github.com/python/cpython/issues/34627/) -- Atomic grouping (`(?>...)`) and possessive quantifiers (`*+, ++, ?+, {m,n}+`) are now supported in regular expressions. * The [Faster CPython Project](https://github.com/faster-cpython/) is already yielding some exciting results. Python 3.11 is up to 10-60% faster than Python 3.10. On average, we measured a 1.22x speedup on the standard benchmark suite. See [Faster CPython]( https://docs.python.org/3.11/whatsnew/3.11.html#faster-cpython) for details. ## Typing and typing language changes * [PEP 673](https://www.python.org/dev/peps/pep-0673/) -- Self Type * [PEP 646](https://www.python.org/dev/peps/pep-0646/) -- Variadic Generics * [PEP 675](https://www.python.org/dev/peps/pep-0675/) -- Arbitrary Literal String Type * [PEP 655](https://www.python.org/dev/peps/pep-0655/) -- Marking individual TypedDict items as required or potentially-missing * [PEP 681](https://www.python.org/dev/peps/pep-0681/) -- Data Class Transforms <small>(Hey, **fellow core developer,** if a feature you find important is missing from this list, [let Pablo know](mailto:pablogsal@python.org ).)</small> The next pre-release of Python 3.11 will be 3.11.0rc2, currently scheduled for Monday, 2022-09-05. # More resources * [Online Documentation](https://docs.python.org/3.11/) * [PEP 664](https://www.python.org/dev/peps/pep-0664/), 3.11 Release Schedule * Report bugs at [ https://github.com/python/cpython/issues](https://github.com/python/cpython… . * [Help fund Python and its community](/psf/donations/). # And now for something completely different A quark star is a hypothetical type of compact, exotic star, where extremely high core temperature and pressure have forced nuclear particles to form quark matter, a continuous state of matter consisting of free quarks. Some massive stars collapse to form neutron stars at the end of their life cycle, as has been both observed and explained theoretically. Under the extreme temperatures and pressures inside neutron stars, the neutrons are normally kept apart by degeneracy pressure, stabilizing the star and hindering further gravitational collapse. However, it is hypothesized that under even more extreme temperature and pressure, the degeneracy pressure of the neutrons is overcome, and the neutrons are forced to merge and dissolve into their constituent quarks, creating an ultra-dense phase of quark matter based on densely packed quarks. In this state, a new equilibrium is supposed to emerge, as a new degeneracy pressure between the quarks, as well as repulsive electromagnetic forces, will occur and hinder total gravitational collapse. If these ideas are correct, quark stars might occur, and be observable, somewhere in the universe. Theoretically, such a scenario is seen as scientifically plausible, but it has been impossible to prove both observationally and experimentally because the very extreme conditions needed for stabilizing quark matter cannot be created in any laboratory nor observed directly in nature. The stability of quark matter, and hence the existence of quark stars, is for these reasons among the unsolved problems in physics. # We hope you enjoy the new releases! Thanks to all of the many volunteers who help make Python Development and these releases possible! Please consider supporting our efforts by volunteering yourself or through organization contributions to the Python Software Foundation. https://www.python.org/psf/ If you have any questions, please reach out to me or another member of the release team :) Your friendly release team, Ned Deily @nad https://discuss.python.org/u/nad Steve Dower @steve.dower https://discuss.python.org/u/steve.dower Pablo Galindo Salgado @pablogsal https://discuss.python.org/u/pablogsal

2 1

Re: Trying to understand nested loops
by Dan Purgert Aug. 8, 2022

Aug. 8, 2022

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 dn wrote: > On 06/08/2022 11.41, avi.e.gross(a)gmail.com wrote: >> I wonder if someone is pulling our leg as they are sending from an >> invalid email address of "GB <NOTsomeone(a)microsoft.invalid>" which is >> a bit sick. > > There are a number of folk who use evidently false email addresses - the > OP's had me amused. > > Such 'hiding' is a matter for the List-Admins (thanks for all the work > exerted on our behalf!) and how it fits with the Code-of-Conduct. Invalid sending addresses (email(a)somewhere.invalid) are a standard practice in Usenet, to combat bots scraping posts for email addresses (remember, Usenet predates basically all spam prevention tech). As there is a gateway between the mailing lists and Usenet, I *imagine* that the use of said invalid addresses are within the rules -- I mean, if they weren't, the maintainers wouldn't keep the two lists connected. -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEE3asj+xn6fYUcweBnbWVw5UznKGAFAmLw+rkACgkQbWVw5Uzn KGBT4A/8DR8GWlEgZhcoaLYTnQCfBv8YmykUxQ69/Xwf7o34S/ObtN0WTapgEBkB xamJHzFKENVeOoFwNgWkAaLSfOm2704DqO4vEJBZmCGrPtLTjHmpQuIcg2c+cjwz EEaYCuWmQZrviFS9ZeWX4FIMX9IlZ3Sgy7e/qHvdI5jeclw4oltYdRxVO3h9WylM BXn3Lvqntw+/5xV3vI/B2SODBTkB8a4D0vC64a3NwGqA3eUkyZrJYlVX8igubBwJ /sDLTy9EOK7wmokoXIHjj7KN+s5bC8idUN/V6DJiE6Z3vU0AOujKsw8jyQbndP9d 7da3gDLECMTHTFuKkj8kWC005aaWdM+GYzm1nofQC0jpINCP88IVce9curm11IQa AVWmxNBuGtLh8E3iE5WaydkgwZJXAll2cewOtzyJ0H8qeMwcqtL7hcKwdVPSzSYG JDqcbthDAzJg/PXcLjBHidXNZQ1BhyLw9ySzf+/7buiSsMdHuYZEohHXH4ybRMtL hlg6r09b5nDbKD7C9hVfL21+mogcX9t+LehsqiPLXssyMHRpTmGRzQ+CBySg5QaV gXshFJxRqvp9UtL+xw/wNL3wODsaVTU430qSKUI1ov7ClqcUXvEP5cbmKa9ufJ/J 8iDSbAP2B54pGyF9hfF0f8h267bZy13gWWqBqiFoCBZcVkaC/Jo= =6yDi -----END PGP SIGNATURE----- -- |_|O|_| |_|_|O| Github: https://github.com/dpurgert |O|O|O| PGP: DDAB 23FB 19FA 7D85 1CC1 E067 6D65 70E5 4CE7 2860

2 1

Information about Dying kernel
by nhlanhlah198506 Aug. 8, 2022

Aug. 8, 2022

Greetings What can I do if my computer said my kernels has died Thank you Sent from my Galaxy

3 2

Python gets a mention on Reddit - in r/tifu
by Skip Montanaro Aug. 7, 2022

Aug. 7, 2022

Not exactly where I expected to see Python mentioned on Reddit, but I found this amusing (yes, despite the subreddit, it should be safe for work): https://www.reddit.com/r/tifu/comments/wibmkh/tifu_by_teaching_my_13yo_brot… Just a little diversion for a Sunday afternoon. I was particularly amused, as my son is in dev ops, writes Python from time-to-time, and my grandson is 13. I could definitely see the pattern in the story transferring over to Chris and Carmine. Skip

1 0

Re: SyntaxError: multiple statements found while compiling a single statement
by Joe Pfeiffer Aug. 7, 2022

Aug. 7, 2022

Sohail Ahmad <sohailahmad2594(a)gmail.com> writes: > kindly please help me about issues > SyntaxError: multiple statements found while compiling a single statement how to solve this issues Please post the code that got the error. Preferably several lines before the actual error, and the line with the error itself.

1 0

Re: Trying to understand nested loops
by GB Aug. 6, 2022

Aug. 6, 2022

On 05/08/2022 08:56, Frank Millman wrote: > BTW, there is an indentation error in your original post - line 5 should > line up with line 4. As a Python beginner, I find that Python is annoyingly picky about indents. And, the significance of indents is a bit of a minefield for beginners. For example, in the above code, the indent of the final line very significantly affects the results: print(var) print(var) print(var) These are all different.

8 13

Re: Trying to understand nested loops
by Mladen Gogala Aug. 6, 2022

Aug. 6, 2022

On Fri, 5 Aug 2022 08:34:45 +0100, ojomooluwatolami675 wrote: > Hello, I’m new to learning python and I stumbled upon a question nested > loops. This is the question below. Can you please how they arrived at 9 > as the answer. Thanks > > var = 0 for i in range(3): > for j in range(-2,-7,-2): > var += 1 > print(var) > > Sent from my iPhone That's simple. Number 9 itself is equal to 3*3. Inner loop executes 3 times for each of the 3 executions of the outer loop. PS: The reply is intentionally written in such a way that it cannot be used as an answer to a homework question. You'll have to work out the details yourself. -- Mladen Gogala Database Consultant https://dbwhisperer.wordpress.com

1 0

Trying to understand nested loops
by ojomooluwatolami675＠gmail.com Aug. 6, 2022

Aug. 6, 2022

Hello, I’m new to learning python and I stumbled upon a question nested loops. This is the question below. Can you please how they arrived at 9 as the answer. Thanks var = 0 for i in range(3): for j in range(-2,-7,-2): var += 1 print(var) Sent from my iPhone

8 7