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

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.
  • Top 20 packages are all downloaded over 1.3 million times per day.

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