lystn

Watch the live stream:

About the show

Sponsored by us:

• Check out the courses over at Talk Python
• And Brian’s book too!

Special guest: Chris Moffit

Brain #1: Subclassing in Python Redux

• Hynek Schlawack
• Prefer composition over inheritance,
• But if you must subclass, there are 3 types
  • subclassing for code sharing
  • bad. don’t do it.
  • read the article and included linked articles if you aren’t convinced
  • Interfaces / Abstract Data Types
  • Can be useful, but Python has tools that make this work without subclassing
  • Specialization
  • Exception hierarchies
  • There’s also an interesting discussion of structuring data classes with common elements
  • This is the only type of subclassing that Hynek deems worthy
• This is a well written, useful, and long-ish article that I cannot summarize and do it justice.
• My summary: If you even consider sublcassing other than for exceptions, read this article first.

Michael #2: Extra, Extra, Extra*7, Hear all about it!

• New course! Python-powered chat apps with Twilio and SendGrid
• Pyodide is now an independent project
• Wow textual from Nick Mouh
• #NoFLOC for real!
• Need to protect your Python source? SourceDefender **(commercial product, but neat)
• I was a guest on A Day in a Life of a WFH Pythonista. Full episode starts here, and the studio/office tour here.
• Python 3.9.6 is out
• Python Web Conf 2021 videos are out, including mine on memory.
• pip install pythonbytes via pythonbytes package.

Chris #3: klib

• Perform automated cleaning and analyzing of data in a pandas DataFrame
• Missing value plot and correlation data plots are similar to other tools but the visualizations are nicely done and useful.
• The data cleaning functions are really nice. In some testing, the automated data type conversion can save a meaningful amount of data.
• For large data sets, you can drop columns with lots of null values or highly correlated values.
• The clean_column_names function also performs several cleanups on column names such as removing spaces, standardizing CamelCase, etc.
• You have control to use as much or as little of the automated process as possible.

Brian #4: Don’t forget about functools

• “functools — Higher-order functions and operations on callable objects”
  • in English: cool decorators and other functions that act on functions
• A recent article by Martin Heinz reminded me to review functools
• We’ve talked about singledispatch recently, and I’m sure we’ve talked about lru_cache before. These are in functools.
• functools is an interesting library in that you kind of use it more and more as you increase your Python experience. As a new Python dev, I would have been rather lost looking at this, but as you work through different projects, come back to this and have a look, it’ll have stuff you probably could have used, and will use in the future.
• What’s in there? Here’s a few:
  • @singledispatch & @singledispatchmethod - function/method overloading
  • @wraps - A must for creating your own decorators that makes the decorated function act just like the original function (attributes, docstring, and all, with just the added behavior you are adding.
  • @lru_cache - memoization made easy
  • LRU = least recently used. It’s what it throws away when it’s full
  • @cache - like @lru_cache but with no max size. New in 3.9
  • @cached_property - only run the read code once. New in 3.8
  • del(obj.property) to clear it. Yes this is weird, but also cool.
  • @total_ordering - Define __eq__() and one other ordering function and get the other ordering functions for “free”.
    • not free. cost is slower execution and confusing stack traces if things go wrong. but still, when prototyping something, or when comparisons are very rare, this is cool
  • partial / partialmethod - create a new function with some of the arguments of the old function already filled in.
  • super cool for callbacks or defining convenience functions

Michael #5: GitHub Copilot

• Get suggestions for whole lines or entire functions right inside your editor.
• Available today as a Visual Studio Code extension.
• The technical preview does especially well for Python, JavaScript, TypeScript, Ruby, and Go, but it understands dozens of languages and can help you find your way around almost anything.
• You can cycle through alternative suggestions
• Powered by Codex, the new AI system created by OpenAI
• Based on gpt3.

Chris #6: Kats

• New tool from facebook for Time Series analysis
• Can use Facebook’s Prophet as well as other algorithms such as Sarima and Holt-Winters for prediction. Here’s my old post on prophet.
• Some controversy about how well prophet performs in real life. Very detailed article here.
• Provides utilities for analyzing time series including outlier and seasonality detection
• Offers advanced ensemble methods and access to deep learning algorithms

Extras

Chris

• Unyt - library for working with units of measure. Pint is another similar one with a different API.

Jokes

Italian Aysnc (from Dean Langsam)

Q: Why aren't cryptocurrency engineers allowed to vote? A: Because they're miners!