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Regarding importing from a sub-directory
by Phil Feb. 11, 2024

Feb. 11, 2024

There's no need Alan, to post either of my previous messages to the list. I have discovered the answer to the problem. It's IDLE that's the problem. VS Code does not have a problem importing from a sub_directory. -- Regards, Phil

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Importing a class from a sub-directory
by Phil Feb. 10, 2024

Feb. 10, 2024

Thank you for reading this and this is a problem that I've struggled with for quite some time. The simple fix was to copy myclass into whatever project directory that I was working on at the time, but of course, this means that I have to maintain multiple copies of the same class. Say I have myclass.py saved in ~/Python and I want to import myclass into myproject.py that is saved in ~/Python/Tkinter/myproject. How do I do that? I have tried countless possibilities including: from ..myclass import Myclass I've created a file named "__init__.py and saved myclass.py into that file I've tried from "~/Python/myclass" import Myclass but that's a syntax error I've scoured the Internet looking for a solution and read several tutorials and even consulted my AI friends and I'm still at a lose to solve this seemingly simple problem. Using the tree command I have confirmed that I have the following directory structure: ~/Python |__ myclass.py |__ Tkinter |_ myproject.py -- Regards, Phil

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MTG: pytest (NZPUG, Auckland, VacExcHndlrs)
by dn Jan. 31, 2024

Jan. 31, 2024

Wed 7 Feb (evening NZDT) will be the last virtual gathering in the current Vacation Exception Handlers (VacExcHndlrs) series (https://danceswithmice.info/Python/2024/VacExcHndlrs.html). You are cordially-invited to join us to investigate the pytest Python testing framework. "The pytest framework makes it easy to write small, readable tests, and can scale to support complex functional testing for applications and libraries." Pre-requisites: 1 Head-set to ask questions and make contributions 2 Lab-/Log-/Note-book 3 Python 3.8+ installed 4 Ability to write intro-level Python program[me]s (at least) 5 Credentials to install from PyPi ("The Cheese Shop") 6 Preparedness to research, experiment, work with others... As before, we will follow a café style of meeting. So, come prepared with a list of objectives you would like to achieve and a list of achievements you will be ready to share. Possible (but far too many) topics: - installing pytest (individual, system-wide, PyCharm, VSCodium, ...) - TDD's (Test-Driven Development) red-green refactoring - the Python assert-statement - the project directory-tree and auto-discovery - adding simple-tests - running pytest - reporting - structuring the code-base to facilitate testing - advantages/disadvantages of automated testing - using a GAI to suggest/generate tests - fixtures and dependencies (set-up and/or tear-down) - scopes (function, class, module, session) - parametrizing - monkey-patching - CI/CD chaining you've built - plug-ins you're finding helpful - coverage - testing strategies - other testing frameworks and aids (open-ended - what would you like to add?) Come to participate, learn-from, and help others! Please RSVP at https://www.meetup.com/nzpug-auckland/events/298901851/ -- Regards, =dn

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Cryptography
by Simon Connah Jan. 31, 2024

Jan. 31, 2024

Hi, I need to implement a way to securely sign a value in a cookie to make sure that it has not been tampered with. I've been playing around with the cryptography library and it does what I need but I'm stuck on secure locations to store the private key and the password required to decrypt it. Having said that I have experience with GnuPG because I use it for other things and was wondering if that would be a more sensible choice. I mean it doesn't matter too much if they get exposed as it is only to ensure that cookie data is correct. I'm not using it for secrecy. So I thought I'd ask here about what the best practice is for generating, storing and encrypting key pairs in Python. I'm using the Flask framework and the MongoDB database. Simon.

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How to create a binary tree hierarchy given a list of elements as its leaves
by marc nicole Jan. 31, 2024

Jan. 31, 2024

So I am trying to build a binary tree hierarchy given numerical elements serving for its leaves (last level of the tree to build). From the leaves I want to randomly create a name for the higher level of the hierarchy and assign it to the children elements. For example: if the elements inputted are `0,1,2,3` then I would like to create firstly 4 elements (say by random giving them a label composed of a letter and a number) then for the second level (iteration) I assign each of 0,1 to a random name label (e.g. `b1`) and `2,3` to another label (`b2`) then for the third level I assign a parent label to each of `b1` and `b2` as `c1`. An illustation of the example is the following tree: [image: tree_exp.PNG] For this I use numpy's `array_split()` to get the chunks of arrays based on the iteration needs. for example to get the first iteration arrays I use `np.array_split(input, (input.size // k))` where `k` is an even number. In order to assign a parent node to the children the array range should enclose the children's. For example to assign the parent node with label `a1` to children `b1` and `b2` with range respectively [0,1] and [2,3], the parent should have the range [0,3]. All is fine until a certain iteration (k=4) returns parent with range [0,8] which is overlapping to children ranges and therefore cannot be their parent. My question is how to evenly partition such arrays in a binary way and create such binary tree so that to obtain for k=4 the first range to be [0,7] instead of [0,8]? My code is the following: #!/usr/bin/python # -*- coding: utf-8 -*- import string import random import numpy as np def generate_numbers_list_until_number(stop_number): if str(stop_number).isnumeric(): return np.arange(stop_number) else: raise TypeError('Input should be a number!') def generate_node_label(): return random.choice(string.ascii_lowercase) \ + str(random.randint(0, 10)) def main(): data = generate_numbers_list_until_number(100) k = 1 hierarchies = [] cells_arrays = np.array_split(data, data.size // k) print cells_arrays used_node_hierarchy_name = [] node_hierarchy_name = [generate_node_label() for _ in range(0, len(cells_arrays))] used_node_hierarchy_name.extend(node_hierarchy_name) while len(node_hierarchy_name) > 1: k = k * 2 # bug here in the following line cells_arrays = list(map(lambda x: [x[0], x[-1]], np.array_split(data, data.size // k))) print cells_arrays node_hierarchy_name = [] # node hierarchy names should not be redundant in another level for _ in range(0, len(cells_arrays)): node_name = generate_node_label() while node_name in used_node_hierarchy_name: node_name = generate_node_label() node_hierarchy_name.append(node_name) used_node_hierarchy_name.extend(node_hierarchy_name) print used_node_hierarchy_name hierarchies.append(list(zip(node_hierarchy_name, cells_arrays)))

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Crystal Reports with Python.
by Pablo Fleitas Zeni Jan. 21, 2024

Jan. 21, 2024

Hi nice people, I wanto to load crystla report from "*.rpt" and export to ".pdf" I have Crystal Runtime version 13.0 . Someone knows about it? For any informationm, Thanks a lot.

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LLM comparison
by dn Jan. 19, 2024

Jan. 19, 2024

The latest branch of the "Debugging skills" thread involved a casual experiment in using ChatGPT3.5 and Claude2 to help a programmer debug his/her code after Python rejected lines which (s)he reasonably-expected to work. If you haven't been following that thread, and this topic piques your interest, perhaps you'd like to review the former and add your reactions or comments? Meantime, I approached the problem in (what seems to me) the more common mode ('what the kids are doing today'): by presenting the LLM with the problem itself, and asking the 'AI' to generate code. The wording is in a slightly pompous, academic style, in order to extract comparative-responses:- Question: The requirement is a Python function which given an integer-number, will return a list populated with values equal to that value's index or relative-position in the list. Please provide three answers: (1) code likely to be produced by a Python-Beginner, (2) code likely to be produced by an Intermediate-level programmer, and (3) code from a Python-Master. ChatGPT3.5: Certainly! Here are three versions of the Python function as per your request: 1. **Beginner Level:** ```python def beginner_function(number): result_list = [] for i in range(number): result_list.append(i) return result_list ``` 2. **Intermediate Level:** ```python def intermediate_function(number): return [i for i in range(number)] ``` 3. **Python Master Level:** ```python from itertools import range def master_function(number): return list(range(number)) ``` These implementations achieve the same result, creating a list with values equal to their index or relative position in the list, but differ in terms of simplicity, conciseness, and utilization of advanced features of Python. Claude2: Here are three potential solutions to the given problem at different Python experience levels: 1. Beginner solution: ```python def populate_list(num): new_list = [] for i in range(num): new_list.append(i) return new_list ``` 2. Intermediate solution: ```python def populate_list(num): return list(range(num)) ``` 3. Expert solution: ```python populate_list = lambda num: list(range(num)) ``` The beginner creates an empty list first and uses a for loop to append each index. The intermediate programmer leverages the built-in range() function and typecasts it to a list directly. The expert uses a lambda function to achieve the same result as the intermediate solution, but in a simple one-liner expression. In summary, the solutions showcase Pythonic techniques getting more advanced from basic procedural logic to built-in functions to functional programming. Thus, the question elicited expected responses. What do you think? Both of the 'Expert solutions' contained rather 'frilly bits' - perhaps an attempt to convince us of Mastery rather than a true demonstration thereof? The first/Beginner-level responses are essentially-identical. Would you expect that most folk improving the Beginner's 'traditional' for-loop approach would graduate to a list-comprehension? There was no need for ChatGPT (response 3) to import itertools (it's not used anyway) - the built-in function does the job. That Claude2 failed to suggest a list-comprehension was a surprise. What do you think? Do you agree that Claude2's proposition of a lambda as "simple one-liner" demonstrates mastery? Indeed is that 'better' than its own 'Intermediate solution'? Between the two LLMs, compare their choices of names. How do they contribute to a reader's comprehension (ignoring the lack of docstrings, or indeed imagining that such are present). What do you think (particularly if was part of a much larger code-base)? Other thoughts? -- Regards, =dn

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Debugging skills
by ThreeBlindQuarks Jan. 15, 2024

Jan. 15, 2024

After some recent discussions here, I think the best gift for some learners is learning debugging skills. As an example Mr. Rosenberg probably could benefit from writing small amounts of code then stopping and testing the results up to that point to see if it was what was expected. You can use Python very interactively including various methods of cutting and pasting or a line or region at a time if using RSTUDIO to run it. So it can be useful to people to run some code, pause and check things like what is the current content of a variable, what "type" python thinks it is or if it is a composite object like a class, examine some of the contents. I am not talking about a formal debugger, just fairly basic stuff. When you encounter an error message, you definitely should not proceed with more code until it has been dealt with as some errors make the rest of your code be treated as nonsense. And, certainly, there are debuggers you can learn and use but mostly there is no need. If you do things like this and then still hit a wall, you can then ask a question here more intelligently and using the minimal amount of code that reproduces the error. Ages ago, I used to work and teach with programs written on punch cards and handed in and received back hours or days later. Those were primitive times where you felt you had to write a whole progra before submitting it. That is not the case with Python and incremental work is often a decent approach as long as you have a good editor or setup and know how to make sure to write modular code that can be tested and debugged in small chunks. The other thing to keep remembering is that when programming in a language, ONLY the rules for that language apply. Sometimes people forget that python uses indentation quite precisely and although extra parentheses and other kinds of brackets may seem harmless, sometimes they really aren't. Because of the indentation issues, unlike some other languages, copying code from one place to another, or just moving it within a program generally causes problems as it may not be aligned as expected. And some symbols simply do not mean the same thing as in some other language such as curly braces generally are reserved for a set or dictionary and not for grouping. I think people have a tendency to jump ahead and do more challenging things before they have mastered the basics. I know I often do but I also know enough to back away and examine my environment when things are not working or even switch to other methods I know already. My guess is some people are using a resource, such as an online list of programming exercises that are not really designed as a teaching experience where each section extends what has already been learned. They may be better off with some more formal course such as some of the free course on coursera or perhaps paid versions that do better grading and offer a certificate: https://www.coursera.org/search?query=python& Of course, if you are someone like me who mainly learns languages these days as a sort of hobby, ...

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Mtg: Object-Oriented VacExcHndlrs (UTC+13)
by dn Jan. 14, 2024

Jan. 14, 2024

Let's meet on Wednesday (17Jan, 1600 NZDT (UTC+13), wearing a head-set) to talk about Object-Oriented everything. Is O-O worthwhile, or does is it just a load of guys running around and getting no-where? NB this is not a formal PUG-meeting. It's part of the "Vacation Exception Handlers" series (https://danceswithmice.info/Python/2024/VacExcHndlrs.html) - virtual-gatherings for folk left-behind to keep the wheels turning, whilst everyone else swans-off sunning themselves... (non-Kiwis please remember: it's not just school vacation, but summer-time down-under. Wish you were here?) Café-style approach, so there will be no formal presentation. All welcome. No presumption of knowledge/skill. This gathering is for everyone, from Beginner to Python-Master. Is Python an Object-Oriented language? Why does Python use (what appear to be) procedural constructs for so many of its core functions, eg len(a_list) rather than a_list.length() and sqrt(a_number) rather than a_number.sqrt()? Why do pythonista say "everything in Python is an object"? Is it faster to write in an OOP-style and/or does OOP-code run faster? If not, why bother? - insert your question here: What do you want to know? What has been bothering you about OOP (or O-O in Python) that you'd like to settle? To join us (we don't bite!), please RSVP at https://www.meetup.com/nzpug-auckland/events/298536620/ -- Regards, =dn

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best tool to extract domain hierarchy from a dimension in an OLAP dataset (csv)
by marc nicole Jan. 12, 2024

Jan. 12, 2024

Hi all, I have a csv OLAP dataset that I want to extract the domain hierarchies from each of its dimensions. Anybody could recommend a Python tool that could manage this properly? Thanks

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