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Episode #164: Use type hints to build your next CLI app

Published Thurs, Jan 16, 2020, recorded Thurs, Jan 9, 2020.

Sponsored by Datadog: pythonbytes.fm/datadog

Michael #1: Data driven journalism via cjworkbench

  • via Michael Paholski
  • The data journalism platform with built in training
  • Think spreadsheet + ETL automation
  • Designed around modular tools for data processing -- table in, table out -- with no code required
  • Features include:
    • Modules to scrape, clean, analyze and visualize data
    • An integrated data journalism training program
    • Connect to Google Drive, Twitter, and API endpoints.
    • Every action is recorded, so all workflows are repeatable and transparent
    • All data is live and versioned, and you can monitor for changes.
    • Write custom modules in Python and add them to the module library

Brian #2: remi: A Platform-independent Python GUI library for your applications.

  • Python REMote Interface library.
  • “Remi is a GUI library for Python applications which transpiles an application's interface into HTML to be rendered in a web browser. This removes platform-specific dependencies and lets you easily develop cross-platform applications in Python!”
  • No dependencies. pip install git+https://github.com/dddomodossola/remi.git doesn’t install anything else.
  • Yes. Another GUI in a web page, but for quick and dirty internal tools, this will be very usable.
  • Basic app:
    import remi.gui as gui
    from remi import start, App

    class MyApp(App):
        def __init__(self, *args):
            super(MyApp, self).__init__(*args)

        def main(self):
            container = gui.VBox(width=120, height=100)
            self.lbl = gui.Label('Hello world!')
            self.bt = gui.Button('Press me!')
            self.bt.onclick.do(self.on_button_pressed)
            container.append(self.lbl)
            container.append(self.bt)
            return container

        def on_button_pressed(self, widget):
            self.lbl.set_text('Button pressed!')
            self.bt.set_text('Hi!')

    start(MyApp)

Michael #3: Typer

  • Build great CLIs. Easy to code.
  • Based on Python type hints.
  • Typer is FastAPI's little sibling. And it's intended to be the FastAPI of CLIs.
  • Just declare once the types of parameters (arguments and options) as function parameters.
  • You do that with standard modern Python types.
  • You don't have to learn a new syntax, the methods or classes of a specific library, etc.
  • Based on Click
  • Example (min version)
    import typer

    def main(name: str):
        typer.echo(f"Hello {name}")

    if __name__ == "__main__":
        typer.run(main)

Brian #4: Effectively using Matplotlib

  • Chris Moffitt
  • “… I think I was a little premature in dismissing matplotlib. To be honest, I did not quite understand it and how to use it effectively in my workflow.”
  • That very much sums up my relationship with matplotlib. But I’m ready to take another serious look at it.
  • one reason for complexity is 2 interfaces
    • MATLAB like state-based interface
    • object based interface (use this)
  • recommendations:
    • Learn the basic matplotlib terminology, specifically what is a Figure and an Axes .
    • Always use the object-oriented interface. Get in the habit of using it from the start of your analysis.
    • Start your visualizations with basic pandas plotting.
    • Use seaborn for the more complex statistical visualizations.
    • Use matplotlib to customize the pandas or seaborn visualization.
  • Runs through an example
  • Describes figures and plots
  • Includes a handy reference for customizing a plot.
  • Related: StackOverflow answer that shows how to generate and embed a matplotlib image into a flask app without saving it to a file.
  • Style it with pylustrator.readthedocs.io :)

Michael #5: Django Simple Task

  • django-simple-task runs background tasks in Django 3 without requiring other services and workers.
  • It runs them in the same event loop as your ASGI application.
  • Here’s a simple overview of how it works:
    1. On application start, a queue is created and a number of workers starts to listen to the queue
    2. When defer is called, a task(function or coroutine function) is added to the queue
    3. When a worker gets a task, it runs it or delegates it to a threadpool
    4. On application shutdown, it waits for tasks to finish before exiting ASGI server
  • It is required to run Django with ASGI server.
  • Example
    from django_simple_task import defer

    def task1():
        time.sleep(1)
        print("task1 done")

    async def task2():
        await asyncio.sleep(1)
        print("task2 done")

    def view(requests):
        defer(task1)
        defer(task2)
        return HttpResponse(b"My View")

Brian #6: PyPI Stats at pypistats.org

  • Simple interface. Pop in a package name and get the download stats.
  • Example use: Why is my open source project now getting PRs and issues?
  • I’ve got a few packages on PyPI, not updated much.
    • cards and submark are mostly for demo purposes for teaching testing.
    • pytest-check is a pytest plugin that allows multiple failures per test.
  • I only hear about issues and PRs on one of these. So let’s look at traffic.
    • cards: downloads day: 2 week: 24 month: 339
    • submark: day: 5 week: 9 month: 61
    • pytest-check: day: 976 week: 4,524 month: 19,636
  • That totally explains why I need to start actually supporting pytest-check. Cool.
  • Note: it’s still small.

Extras:

  • Comment from January Python PDX West meetup
    • “Please remember to have one beginner friendly talk per meetup.”
    • Good point.
    • Even if you can’t present here in Portland / Hillsboro, or don’t want to, I’d love to hear feedback of good beginner friendly topics that are good for meetups.
  • PyCascades 2020

    • discount code listeners-at-pycascades for 10% off
  • FireFox 72 is out with anti-fingerprinting and PIP - Ars Technica

Joke:

Language essays comic


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