Python Bytes 29

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Brian #1: Responsive Bar Charts with Bokeh, Flask and Python 3

• by Matt Makai at fullstackpython.com
• A walkthrough example of putting together a flask app that uses Bokeh bar charts to visualize data.
• All steps included, no previous experience with Flask or Bokeh required.
• Nice explanation of what the code does without going into too much detail.
• Good jumping off point for further learning, but complete enough to be useful right away.

Michael #2: Zappa Serverless Python Web Services

• Zappa makes it super easy to build and deploy all Python WSGI applications on AWS Lambda + API Gateway
• Think of it as "serverless" web hosting for your Python apps.
• That means infinite scaling, zero downtime, zero maintenance - and at a fraction of the cost of your current deployments!
• Better still, with Zappa you only pay for the milliseconds of server time that you use, so it's many orders of magnitude cheaper than VPS/PaaS hosts and in most cases, it's completely free. Plus, there's no need to worry about load balancing or keeping servers online ever again.
• Asynchronous Task Execution:

    from flask import Flask
    from zappa.async import task
    app = Flask(__name__)

    @task
    def make_pie():
        """ This takes a long time! """
        ingredients = get_ingredients()
        pie = bake(ingredients)
        deliver(pie)

    @app.route('/api/order/pie')
    def order_pie():
        """ This returns immediately! """
        make_pie()
        return "Your pie is being made!"

Brian #3: Using a local cache for pip packages

• In https://pythonbytes.fm/24, Local package store, we talked about using pip to cache pypi projects to allow offline installation:
  • $ pip download --cachedir [HTML_REMOVED]
  • $ pip install --no-index --find-links=/tmp/wheelhouse somePackage
• Well, Dominic does us one better by wrapping these commands in a couple of aliases.
• However, his version uses pip install --``download, which has been deprecated. Here’s a version with the new syntax:
  • alias pipcache='pip download --cache-dir ${HOME}/.pip-packages'
  • alias pipinstall='pip install --no-index --find-links=file://${HOME}/.pip-packages/'

Michael #4: Building game AI using ML: Working with TensorFlow, Keras, and the Intel MKL in Python

• From the ActivePython guys
• a classic arcade space shooter game that features enemies powered by machine learning
• we decided to build a Neural Network to drive the behaviour of the enemies in the game
• For the game part of things, we’re using PyGame
• In the training mode, the enemies fire randomly, and then each shot taken by the enemy is recorded as a hit or a miss along with its initial relative position/velocity values. Every one of these shots becomes a row in the training matrix and the network is trained in “realtime” after every row is added so you can see the network build and develop as you train.
• LESSONS LEARNED
  • Choosing the right data to train your network is important.
  • “Prepping” your data is key.
  • Experiment with network topology.
  • Visualization is important.

Brian #5: Debug Test Failures With Pdb

• by Raphael Pierzina
• Debugging code with pytest, using:
  • --pdb to jump into the debugger at the point of failure
  • -x to stop after first failure
  • --lf to re-run all the tests that failed last time
• Note: Yes. All this and more is covered in Python Testing with pytest.
  • Shameless plug for my book. Raphael is one of the technical reviewers.
  • Thank you, Raphael!

Michael #6: Monitoring my VOIP provider with Home Assistant

• Integrating it into Home Assistant: Use home-assistant.io as a home automation platform in my house.
• It’s written in Python, open source, and has a large community surrounding it.
• Unfortunately, there wasn’t anything already built for my Cisco ATA.
• Decided to write, an open source my first python module called pyciscsospa you can download it and use it for your own ATA as well.
• Receive a push notification on my phone when the phone lines go down and come back up