Python Notes: Introduction

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The information presented here is provided free of charge, as-is, with no warranty of any kind.
Edit: 2024-12-07

Introduction
- Hacking-Noodling with BASIC
- Hacking-Noodling with Python
my example Python programs
Shifting over to Python
mod_cgi vs mod_wsgi (experiments)
Machine Learning + Deep Learning
External Links

Introduction

Hacking - Noodling with BASIC

Anyone who played with BASIC on personal computers in the 1970s and 1980s will recognize the importance of the BASIC language for noodling around. The creators of BASIC intended it for use in teaching computer programming concepts to FORTRAN students at Dartmouth College (photo), but noodling around made BASIC ideal for teaching other concepts in science, engineering, and math all over the world.

BASIC on 8-bit personal computers in the 1970s was usually implemented in ROM, and every implementation was different (Apple2, Radio Shack TRS-80, HeathKit-H8). Starting with the IBM-PC in 1981, Microsoft, began publishing 16-bit software products like GW-BASIC (1983), QuickBASIC (1985) and QBASIC (1991) which worked well on 16-bit operating systems like MS-DOS (1981) up through Windows-3.11 (1992). These 16-bit language interpreters were also supported on 32-bit operating systems, starting with Windows-95 up through Windows-7.

The big problem today is that 64-bit computers run 64-bit operating systems, like Windows-10, where 32-bit programs are supported via THUNKING, but native support for 16-bit programs has been dropped. Technical work-arounds exist including "setting up a virtual machine" on your 64-bit OS, but why go to all that bother when all you want to do is noodle around? Perhaps it is time for you to ditch BASIC for Python.

Hacking - Noodling with Python

Many people reading this will not know that Python was first created in 1991 to produce an internet-friendly BASIC-like scripting tool for use under CGI (common gateway interface) specification used to extend web server functionality. Python quickly morphed into a language which could easily support both internet servers and clients, as well a standalone applications. Here is a short list:

popular in the scientific analysis of large data sets since the creation of a free third-party Python libraries known as NumPy and SciPy (just two of many)
popular in many financial circles after Wall Street programmers noticed (after the 2008 financial melt down) that many investment decisions were based upon "questionable data" produced from ad-hoc spreadsheet imports. This was one of the reasons for the creation of a free third-party Python library known as Pandas (panel data analysis) which can import almost any spreadsheet format using only 5-6 lines of code.
popular on almost every computer platform (Windows, Macintosh, Linux, UNIX, etc) for any purpose including noodling around because it is available free of charge -AND- appears to be more consistently implemented than BASIC ever was

Python does not have these BASIC imitations:

This BASIC statement PRINT 2^31 (two raised to the thirty-first power) fails with 32-bit signed integers (longword)
- I have used more than a dozen different flavors of BASIC (on mainframes, minicomputers and microcomputers) and none of them supported unsigned integers.
This BASIC statement PRINT 2^63 fails with 64-bit signed integers (quadword)
- this capability was never available on 32-bit VAX but is available on 64-bit AlphaServer and 64-bit Itanium
Some modern BASIC implementations now support 128-bit signed integers (octaword) but most do not support exponentiation past 64-bits.

Python3 has no difficulty with these statements:

This Python3 statement PRINT(2**9999) (e.g. 2^9999) in the IDLE interpreter instantly yields (37x80)+50 numbers.
This Python3 statement PRINT(2**99999) (e.g. 2^99999) in the IDLE interpreter instantly yields a yellow alert with the phrase "Squeezed Text (377 lines)" which can be optionally displayed, or copied to another app via the clipboard.
This Python3 statement PRINT(2**999999) (e.g. 2^999999) in the IDLE interpreter requires a few seconds on a PC to yield a yellow alert with the phrase "Squeezed Text (3763 lines)"

Imagine using numbers this size to index your data arrays

(a few of my) Example Programs (alphabetical order)

link	description	Notes
calendar	a very simple calendar generator	BASIC-to-Python conversion examples
compiling caching	Python compiling - Python file caching	article for nerds and speed demons
dft-fft	Discrete Fourier Transform - Fast Fourier Transform	BASIC-to-Python conversion examples
dh standalone	Diffie-Hellman key exchange demo (interactive)	Python interactive standalone application
dh web	Diffie-Hellman key exchange demo (web)	Python web application (just to show you how)
Easter	compute the date of Easter for any given year	it all starts with determining the date of the first full moon on, or after. the Spring equinox.
fun with floats	fun with floats and decimals	be careful how you initialize float and decimal data; this program also shows how to properly use the exec() function in python3
http website tester	shows how to fetch a web page	this technique works with both http as well as https
https harder demo	shows how to try harder	shows how to connect to an older https site
logical_name_demo	logical name demo	caveat: this will only work on OpenVMS systems
money rounding	money rounding demo	required for GAAP (generally accepted accounting principles)
pix-of-day	picture of the day generator	extracts picture-of-the-day info from a relational database which is then passed to JavaScript. Click this link (https://neilrieck.net) to see it in action: 1) the top right corner will show a NASA chart for last month's CO2 readings 2) eight seconds later, the image and text will switch to something extracted from my database 3) the pictures will cycle back for ten iterations 4) punch PF12 on your browser then click CONSOLE to observe log messages

Shifting over to Python

https://www.python.org/
- https://www.python.org/downloads/
  - download a totally free python interpreter for any platform along with the IDLE integrated development environment (all you really need for noodling)
  - Linux people using the vim editor to develop Python programs would probably want to install the pymode plugin which handles indenting, syntax checking, and flagging PEP-8 rule violations (your family members will see the colors then think you are emulating Elliot Alderson on Mr. Robot)
  - many people use a free IDE called visual studio code (available on most platforms)
- https://docs.python.org/3/tutorial/
Nerd-stuff
- https://www.geeksforgeeks.org/python-programming-language/
- https://www.geeksforgeeks.org/python2-vs-python3-syntax-and-performance-comparison/
- https://www.geeksforgeeks.org/important-differences-between-python-2-x-and-python-3-x-with-examples/
- https://www.zdnet.com/article/microsoft-we-want-you-to-learn-python-programming-language-for-free/
  - “Python for beginners” playlist from Microsoft (this is the original 44)
    https://www.youtube.com/playlist?list=PLlrxD0HtieHhS8VzuMCfQD4uJ9yne1mE6
  - “More Python for beginners” (this is the new 20)
    https://www.youtube.com/playlist?list=PLlrxD0HtieHiXd-nEby-TMCoUNwhbLUnj
  - “Even More Python for Beginners” (this is the newest 31)
    https://www.youtube.com/playlist?list=PLlrxD0HtieHhHnCUVtR8UHS7eLl33zfJ-
- https://www.zdnet.com/article/python-is-eating-the-world-how-one-developers-side-project-became-the-hottest-programming-language-on-the-planet/
Python2 stuff
- https://pythonclock.org/ - Python2.7 will not receive any security updates after 2020 so make sure you use Python3 (or develop a plan to switch over to Python3)
  - https://github.com/python/devguide/pull/344 this link says no security updates after the end of 2019
- https://www.zdnet.com/article/programming-language-python-2-7-code-is-now-frozen-last-release-coming-in-april/
- https://www.zdnet.com/article/goodbye-python-2-programming-language-this-is-the-final-python-2-7-release/ (final end date: 2020-04-20)
Guido van Rossum
- The Story of Python, by Its Creator, Guido van Rossum :: https://www.youtube.com/watch?v=J0Aq44Pze-w (4 mins)
- Creator of Python Programming Language, Guido van Rossum :: https://www.youtube.com/watch?v=7kn7NtlV6g0 (51 mins)

mod_cgi vs mod_wsgi

mod_cgi is an Apache plugin used to support CGI (common gateway interface) which has been around since 1993
- my team employs several thousand python3 programs which are accessed from Apache via mod_cgi on Linux
- almost all of our python3 programs employ the cgi python library to access web data
  - https://docs.python.org/3/library/cgi.html
    - deprecated since python3.11
    - removed in python3.13
mod_wsgi is an Apache plugin used to support passing web data to python
- according to the good folks driving python3 progress, we should all shift from mod_cgi (via the cgi library) to mod_wsgi
  - https://peps.python.org/pep-3333/
my 2-cents worth
- I installed (2024-07-xx) support for mod_wsgi on my Alma Linux system via the dnf package manager like so:
```
$ sudo yum clean all
$ sudo yum makecache
$ sudo yum list py\*mod\*wsgi\*
  Available Packages
  python3-mod_wsgi.x86_64        4.6.4-5.el8                              appstream
  python3.11-mod_wsgi.x86_64     4.9.4-1.el8                              appstream
  python3.12-mod_wsgi.x86_64     4.9.4-2.el8                              appstream
  python38-mod_wsgi.x86_64       4.6.8-5.module_el8.9.0+3633+e453b53a     appstream
  python39-mod_wsgi.x86_64       4.7.1-7.module_el8.9.0+3634+fb2a896c     appstream
$ sudo yum install python39-mod_wsgi
```
- I wrote a half-dozen python-based wsgi demos so can now report that I see no benefit in converting all my cgi-based python programs to wsgi-based python. Such a decision would never pass any risk-reward analysis. So what to do? Since Apache's mod_cgi is not going away anytime soon (if ever):
  - you could write your own cgi-based solution
  - convert from the official python library cgi to the third-party legacy-cgi library ( https://pypi.org/project/legacy-cgi/ )
```
# python stub
import legacy-cgi as cgi
```

Machine Learning - Deep Learning

Executive Summary

Just as it is nearly impossible to develop a working knowledge of Calculus without a working knowledge of Algebra, I am now convinced that you cannot develop a working knowledge Deep Machine Learning without a working knowledge Python
Unlike other programming projects, you cannot develop a deep machine learning application, then publish it, then move onto something else. These systems are only as good as their training data, which means they should constantly be updated (so the programmer becomes a teacher?)
Artificial Intelligence does not mean Artificial Consciousness. While some modern A.I. systems might pass a Turing Test by Joe citizen, a specialist will always be able to do a better job. (think about the Voight-Kampf interview between Rick Deckard and Rachel in the movie Bladerunner. Rachel knew that eating 'raw oysters' was okay but didn't know that serving 'boiled dog' was wrong)

Anyone considering a course on machine learning or deep learning should learn Python immediately where most examples will include one (or more) of these free Python libraries

NumPy	Library to add array support to Python2 Also adds support for matrix mathematics	https://en.wikipedia.org/wiki/NumPy	Community - 2006
scikit-learn	first generation learning library	https://en.wikipedia.org/wiki/Scikit-learn	Google Summer of Code - 2007
TensorFlow	second generation learning library	https://en.wikipedia.org/wiki/TensorFlow	Google - 2015
Keras	second generation learning library	https://en.wikipedia.org/wiki/Keras	Google - 2015
PyTorch	second generation learning library	https://en.wikipedia.org/wiki/PyTorch	Facebook - 2017

The roots of artificial intelligence (and expert systems, and machine learning) go back to the 1940s and 1950s so contain a lot of non-computer terminology. Modern computer technologists might wish to start here:

online (pay)
- https://www.udemy.com/
- https://www.udemy.com/course/build-neural-networks-from-scratch-with-python-step-by-step/ (24 lectures)
  - introduces concepts from first principles using just one neuron
  - does not employ any third-party libraries
  - all example code is easily run-able in visual studio code (all code is available for download from github)
- https://www.udemy.com/course/complete-machine-learning-and-data-science-zero-to-mastery/ (378 lectures)
- https://www.udemy.com/course/complete-python-developer-zero-to-mastery/ (333 python lectures - 21 associated with machine learning and data science)
- Introduction to Machine Learning (Michael L. Littman of Brown University) at https://www.wondrium.com/ ($20 per month; a trial month is free)
online (free)
- https://vas3k.com/blog/machine_learning/ (Extensive one-page overview) quote: Machine Learning is like sex in high school. Everyone is talking about it, a few know what to do, and only your teacher is doing it. If you ever tried to read articles about machine learning on the Internet, most likely you stumbled upon two types of them: thick academic trilogies filled with theorems or fishy fairy-tales about artificial intelligence, data-science magic, and jobs of the future.
- https://www.w3schools.com/ai/default.asp (Artificial Intelligence)
- https://www.w3schools.com/python/python_ml_getting_started.asp (Machine Learning with Python)
- https://www.youtube.com/watch?v=aircAruvnKk - But what is a neural network? Chapter 1, Deep learning by 3Blue1Brown
- https://www.elementsofai.com/
Google (free)
Facebook (free)
- https://research.facebook.com/blog/2018/05/the-facebook-field-guide-to-machine-learning-video-series/
books
- Deep Learning: A Visual Approach - https://nostarch.com/deep-learning-visual-approach - highly recommend with almost every graphic printed in color (so expensive); 736 pages
- Practical Deep Learning - https://nostarch.com/practical-deep-learning-python - recommended; 426 pages

External Links

https://neilrieck.net/dh_demo.html :: Diffie-Hellman key exchange demo (web) <<<--- click here to run real Python code on my Linux server
python floats + decimals
- python_notes_fun_with_floats_and_decimals.html
- python_notes_money_rounding_demo.html
- now compare Python3 to third-gen languages: OpenVMS Notes: floats (subtitled: fun with floats)
Why Radians rather than Degrees? (associated with my DFT-FFT demos)

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Neil Rieck
Waterloo, Ontario, Canada.