🌐 Mailman 3 April 2021 - Python-list - python.org

uninstall
by Sian Doherty May 4, 2021

May 4, 2021

I’m trying to uninstall Python 3.8.5 on Windows 10 Pro 20H2 as I had multiple environments and as a result corrupted them. When I uninstall from control panel, it takes less than a second and says it uninstalled successfully but I can still access python through the command prompt by typing python. Is there a different way to uninstall that isn’t through the control panel? I would have thought I would do that and then clean out the registry separately and the %localappdata%\pip folder. Any thoughts? Thanks in advance Sian Doherty Sent from Mail for Windows 10

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Re: Not found in the documentation
by elas tica May 1, 2021

May 1, 2021

Peter J. Holzer a écrit : > That's why it's called a container. But it also says *what* an object > must contain to be called a container. You could say that an int object > contains an integer value and a str object contains a reference to a > buffer containing the string - but those aren't references to other > objects, so int and str are not containers. This is not how I interpret the wording : a string is a container for containing a reference to the characters the string holds. Depends on what you mean by "reference" and "contain". With the definition given, I cannot decide if a string or a range object is a container or not. For instance, can we say that range(100) contains 42 ? PLR document *states* that tuples, lists, sets are containers but doesn't mention if a string is a container or not. Nevertheless, str has a __contains__ method so if a string is not a container what is the logic ? > > You said that LR is designed to be much more formally defined, and > > favors correctness and completeness. Good, so can you answer this > > question after reading the LR : what is a "token"? Did't find a > > definition. > There is an indirect definition right at the start of chapter 3: "Input > to the parser is a stream of tokens, generated by the lexical analyzer." > So a token is what the unit of output of the lexer. This is the > definition. The rest of the chapter defines the details. As you know, the devil is in the details ;) A bunch of properties doesn't make a definition. What do we need is a characteristic property (necessary and sufficient). > > Is the "is not" operator a token? > Yes. See chapter 2.3.1. > 2.3.1 is about keywords : https://docs.python.org/3/reference/lexical_analysis.html#keywords not tokens (keywords are tokens but this is not the problem here). >From 2.1.5 (Python 3.9 LR) ............... A line ending in a backslash cannot carry a comment. A backslash does not continue a comment. A backslash does not continue a token except for string literals (i.e., tokens other than string literals cannot be split across physical lines using a backslash). A backslash is illegal elsewhere on a line outside a string literal. ............... Giving the above, if "is not" were a token as you are explaining, the following code should be invalid syntax : # ------------ begin code ------------- 42 is\ not [42] # ------------ end code ------------- but this code compiles perfectly (there is a whitespace at the beginning of the second physical line).

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Start Python programming
by Gazoo April 30, 2021

April 30, 2021

I'd like to start learning Python programming. What sites/tutorials could you recommend for beginner, please. -- Gazoo

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text displays on screen only when I click to exit the program
by Quentin Bock April 30, 2021

April 30, 2021

code with comments for context: #Create a text based game where the user must find 3 items before completing a level #imports and variables for game import pygame from pygame import mixer running = True #initializes pygame pygame.init() #creates the pygame window screen = pygame.display.set_mode((1200, 800)) #Title and Icon of window pygame.display.set_caption("3.02 Project") icon = pygame.image.load('3.02 icon.png') pygame.display.set_icon(icon) #setting up font pygame.font.init() font = pygame.font.Font('C:\Windows\Fonts\OCRAEXT.ttf', 16) font_x = 10 font_y = 40 items_picked_up = 0 items_left = 3 #functions to be called later in program def display_instruction(x, y): instructions = font.render("Each level contains 3 items you must pick up in each room." "When you have picked up 3 items, you will advance to the next room, there are 3 rooms.", True, (255, 255, 255)) screen.blit(instructions, (10, 40)) def main(): global running #Game Loop while running: #sets screen color to black screen.fill((0, 0, 0)) #checks if the user quits or exits the window for event in pygame.event.get(): if event.type == pygame.QUIT: running = False display_instruction(font_x, font_y) pygame.display.update() main() please excuse the def main() thing, this doesn't follow a tutorial this is all on my own, and I don't know why the text displays when I close the python window. I appreciate all help :) <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campai…> Virus-free. www.avast.com <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campai…> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

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Re: Not found in the documentation
by elas tica April 30, 2021

April 30, 2021

Le mercredi 28 avril 2021 à 17:36:32 UTC+2, Chris Angelico a écrit : > In what sense of the word "token" are you asking? The parser? You can > play around with the low-level tokenizer with the aptly-named > tokenizer module. It was a good suggestion, and the PLR doesn't mention the tokeniser module. It should, this goes very well with the conversional style it has. # -------------- from tokenize import tokenize from io import BytesIO s="""42 not\ in [42]""" g = tokenize(BytesIO(s.encode('utf-8')).readline) print(*(g), sep='\n') # -------------- outputting: ...................................... TokenInfo(type=57 (ENCODING), string='utf-8', start=(0, 0), end=(0, 0), line='') TokenInfo(type=2 (NUMBER), string='42', start=(1, 0), end=(1, 2), line='42 not in [42]') TokenInfo(type=1 (NAME), string='not', start=(1, 3), end=(1, 6), line='42 not in [42]') TokenInfo(type=1 (NAME), string='in', start=(1, 7), end=(1, 9), line='42 not in [42]') TokenInfo(type=53 (OP), string='[', start=(1, 10), end=(1, 11), line='42 not in [42]') TokenInfo(type=2 (NUMBER), string='42', start=(1, 11), end=(1, 13), line='42 not in [42]') TokenInfo(type=53 (OP), string=']', start=(1, 13), end=(1, 14), line='42 not in [42]') TokenInfo(type=4 (NEWLINE), string='', start=(1, 14), end=(1, 15), line='') TokenInfo(type=0 (ENDMARKER), string='', start=(2, 0), end=(2, 0), line='') ...................................... So "not in" is not a token and the docs are wrong when they say: ...................................... using a backslash). A backslash is illegal elsewhere on a line outside a string literal. ......................................

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c-types Structure and equality with bytes/bytearray
by Michael Hull April 29, 2021

April 29, 2021

Hello everyone, I've been working with ctypes recently, and I've come across what seems to be some slightly confusing behaviour, when comparing ctype's Structure against `bytes` and `bytearray` objects import ctypes class Int(ctypes.Structure): _fields_ = [("first_16", ctypes.c_int8), ("second_16", ctypes.c_int8)] def serialise(self): return ctypes.string_at(ctypes.addressof(self), ctypes.sizeof(self)) i_obj= Int(first_16= 65, second_16=66) print(i_obj.first_16, i_obj.second_16) i_bytes = i_obj.serialise() print(list(i_bytes)) assert type(i_bytes) == bytes i_bytearray = bytearray(i_bytes) print("obj == bytes =>", i_obj==i_bytes) print("bytes == obj =>", i_bytes==i_obj) print("obj == bytearray =>", i_obj==i_bytearray) print("bytearray == obj =>", i_bytearray==i_obj) When I run this (Python 3.6, and Python2.7) , the final 4 print statements give the following: """ obj == bytes => False bytes == obj => False obj == bytearray => True bytearray == obj => True """ Is this a bit strange -- my understanding was that `bytes` and `bytearray` would normally be expected to work quite interchangeably with each other? It also means that: bytearray == obj => True bytes == bytearray => True bytes == obj => False If anyone has any experience in this area, and can let me know if I'm overlooking something silly, and guidance would be gratefully appreciated. Alternatively, I am happy to open up a bug-report if this looks like unexpected behaviour? Best wishes, Mike

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Re: Not found in the documentation
by Matt Wheeler April 29, 2021

April 29, 2021

On Wed, 28 Apr 2021 at 22:18, Dennis Lee Bieber <wlfraed(a)ix.netcom.com> wrote: <snip> > The old range() returned a list, and said list could (in your example) > contain 42. The current range() (equivalent to former xrange() ) is not a > container as retrieving values consumes them from the range. A nitpick -- retrieving values from a range doesn't consume them: ``` >>> r = range(10) >>> r range(0, 10) >>> list(r) [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] >>> list(r) [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] >>> r[0] 0 >>> r[3] 3 >>> list(r) [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] ``` range objects are iterables, not iterators. We can see the consuming behaviour I think you are referring to by calling iter(): ``` >>> i = iter(r) >>> next(i) 0 >>> list(i) [1, 2, 3, 4, 5, 6, 7, 8, 9] ``` -- Matt Wheeler http://funkyh.at

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Re: Not found in the documentation
by elas tica April 28, 2021

April 28, 2021

Le mercredi 28 avril 2021 à 17:36:32 UTC+2, Chris Angelico a écrit : > > if a string or a range object is a container or not. For instance, > > can we say that range(100) contains 42 ? > Not by that definition of container. Which definition? ;) > some objects have references to other objects, and the high level > concept that some objects support the "in" operator for containment > checks. They are similar, in that many objects use "in" to check the > exact same set that they refer to, but they are not the same (for > instance, range(1, 10, 1000000) requires a reference to the "one > million" integer, even though it is not actually part of the range). The problem with range is different because we all know that a range object doesn't hold (= contain) the int's (except the endpoints and the step) we can iterate on, instead a range object computes on the fly the int's it holds. On the contrary, the string "2021" holds the digits, even "2021"*10**6 does. But this discussion is undecidable since the Python Language Reference doesn't provide a decent definition of a container. > What are you actually trying to prove here? What > problem are you solving? Or is this just nitpicking for the sake of > it? I was only looking for basic definitions, unfortunately the official docs are not able to provide : - what is the str value of an int? (we have to wait until Python 3.8.6 docs to get the response) - what is a container ? what does mean "contains references" ? is a string a container or not and where the docs explains the answer? - what is exactly a token? are "is not" or "not in " tokens? > the language definition. CPython, for instance, is in process of > completely rewriting its parser, and what about rewriting and *redesigning* the docs? Is there even a discussion about this? Nobody complains?

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cant use certain commands, leading to more problems
by Rasig Kosonmontri April 28, 2021

April 28, 2021

Hi i was using python for a while and one day i decided to try out a module called "pyinstaller" i installed it with pip and try to run it as a cmdlet, still didnt work i then searched online for solutions and people tell me to try "python -m pyinstaller" to run it directly with python, still didnt work, i tried pip install it again but all requirements were already satisfied so i heard that the microsoft store's version of python tends to hide itself. and so i uninstalled it but when i typed in to a powershell it just directs me to the mircrosoft store's page i then disabled it from doing that and install python from python.org myself but for some weird reason this time it doesnt work at all, 'python' is somehow not recognized as a cmdlet, bash or command. this also happens with gitbash and cmd ive tried repairing python but still doesnt work if you guys have an idea or a solution to this please let me know or help me through Thanks

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Plot maps in 3D
by Jorge Conforte April 28, 2021

April 28, 2021

Hi, I would like know if it is posible to plot the south in north poles in 3D earth maps. I search in google and always all examples is for cylindric projection, like this: bm = Basemap(llcrnrlon=extent[0], llcrnrlat=extent[2], urcrnrlon=extent[1], urcrnrlat=extent[3], projection='cyl', resolution='l', fix_aspect=False, ax=ax) I try to use the spstere or npstere and I didn't have success. I would like know it is possible use these projections to plot 3D data. Thanks, Conrado

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