November 30, 2016

DIY Alexa Raspberry Pi Voice Assistant

Amazon did something really cool. They made their Alexa voice assistant code open source and cross platform. That means instead of buying their Amazon Echo to get a home assistant, you can simply install it on any system you want.

It's actually a fairly straightforward project, especially if you've setup a Raspberry Pi before (or eight #fromthevault)! Basically you're just installing an application, and setting up a microphone and speaker. Nothing fancy.

There are already some great guides for getting started too for both Raspberry Pi and Alexa. I'm just going to direct you to these, give a rough overview, and add some additional tips.

Here it is in action:

Shopping List

For equipment, you'll need:

1. A Raspberry Pi 3 with SD card and USB micro power source:

November 24, 2016

Intro to Python: Hello World! (Part 1 /2)

Many of the projects on this site use a programming language called python. Python is a great language for beginners, because it is designed to be very readable, but it's also very powerful. It is powerful because there are a lot of powerful libraries and APIs that are easy to use made for python, which allows you to write some pretty exciting programs without much code. 

In this post, I walk you through installing python, and running your first program. In the next post I will introduce containers and functions used to make code readable and re-usable. 

Once you have completed both parts, you should have a good understand of the language features I use in the programs on this blog. There is a lot you can do with only a few concepts!

Here are a couple projects to check out once you have completed these tutorials:

Making a simple Twitter Bot
Reddit word counting
Writing an orbit simulator

Now let's get down to business.

Intro to Python: Containers, Functions, and Loops (Part 2 /2)

This is the second post in a series. If you're just getting started, see Part 1.

In the previous post, you got python installed, and ran a simple program. In this section we will use some language features to store data, and re-use code. These are important concepts for all programming languages.

Before we get started, let me warn you to pay attention to your indentation / white space here. Python doesn't care if you use tabs or spaces for white space, but does require that indented blocks are consistent. 


The first container we will look at is a list. A list is rather unsurprisingly just a series of items in a single object. To create a list, you just assign values inside square brackets separated by commas. After it is created you can add values using your_list_name.append(value). 

November 16, 2016

Python N-body Orbit Simulation

Do you ever find yourself thinking "I wish I could do more recreational physics"? If so, today is your lucky day! We're going simulate our very own solar system.

At the end of this tutorial, you should be able to define a hypothetical gravitational system, and graph the paths of the bodies involved over a custom time frame.

This sounds complicated, because usually physics relating to space is considered hard. But it's not that hard! If someone has already broken down the algorithm (which I will do), you just have to understand the rough theory. Then it's no harder than writing a bot. If you've ever studied kinematics, you should also be able to follow along with the physics.

This is also the first in a series of posts. I will be solving this problem again using C++ instead of python, and introducing some High Performance Computing techniques.

If you don't care about theory, you can also skip straight to the program. An intro to python can be found here.

ELI15 Gravitational Theory

We'll start with the difference between weight and mass. Mass is a measure of the matter that makes up an object, and weight is how much force it feels from gravity. So your weight on the Moon and on Earth are different, but your mass is the same. That's because the Moon has less gravity dragging you down man.

November 11, 2016

From the Vault: Arduino Night Writer.

Night Writer

About four years ago, I invited some friends over to try to turn a remote control car into something programmable. We had some trouble finding supplies though, so they just brought beer instead. But we were determined to build something.

I had recently seen this video, and thought we might be able to reproduce it with just a column of LEDs and a long exposure photo.

This project uses the "Persistence of Vision" concept, where the LEDs flash vertical slices of a letter or symbol, and you provide the horizontal movement. Using a long exposure camera allows you to slowly "paint" the light into your image.

First I'll show you some photos from the project. If you want to build your own, keep scrolling for rough build details. As it's "from the vault", it's not a complete walkthrough. It does give you the code you need though, and a photo of the circuit. This would be a good 2nd or 3rd Arduino project.


HPC 4 Life

November 07, 2016

Reddit Data Mining with Python: Are Canadians Really Sorry?

Internationally, Canadians have a reputation for being a sorry lot. In fact, we've even passed a law called "The Apology Act" stating that saying "sorry" does not count as an admission of guilt. A very sensible law indeed.

Is this stereotype true?

We're going to test it in this tutorial, by counting the frequency of apologies in a number of Canadian subreddits. We will do this using python, and a module called praw which provides an interface to the Reddit API.

Then we will generalize the python program to allow us to search any subreddit for any set of words using command line arguments.

The final program can be found here, and an intro to python can be found here.


The first step is to make sure you have python 3 or higher, and the praw module. If you have python 3, praw can be installed simply by running the following command your shell or command prompt:

$>python -m pip install praw

November 05, 2016

Turbo Press - The Aeropress Pour Over

Most of the projects on this site are created with a cup of coffee immediately in reach, and my favourite way to make coffee is with an Aeropress. This device is sort of a hybrid between French Press, and Espresso. It was also created by Aerobie, inventor of the world famous SuperDisc Frisbee!

There are already hundreds of recipes online, many with a cult like following. Checkout some of the winning recipes from the World Aeropress Competitions, featuring advanced techniques like "the turbulent wiggle". 

After hundreds of experiments of my own, I've abandoned the inverted method for what I call the Turbo Press. This is my favourite way to extract a large cup of coffee with a full bold flavour. 

The Turbo Press

  1. Get a medium to large cup, with a volume of roughly 1.5 Aeropress chambers. 

  2. Fire up the kettle, and freshly grind your beans for a paper filter. In step 8, you should have to push down with the force of an enraged child. If it's too easy, grind finer.

  3. Wet a paper filter and place it in the Aeropress over your cup. Fill with one heaping Aeropress scoop, and  turbulently wiggle your Aeropress so the grinds are flat.

  4. Heaping scoop, fine-ish grind.

November 02, 2016

Simple Python Twitter Bot

Twitter Bots

Twitter has some amazing bot personalities; from celebrity impersonators, to genuinely useful automated announcements. It is also probably the first place anyone was exposed to bots and interacted with them. Some of my favourites are BIGBEN and CaptainMarkov. It is also very easy to make a simple bot, especially if you're familiar with python.

In this post, I'm going to walk you through the creation of Mirror_Bot_1000. Mirror_bot_1000 reads tweets when its username is mentioned, and then makes its own tweet with the mirror image.

It's a great example for the simple interactions with Twitter's API because it requires you to read a message, post a message, and keep track of where you left off. If you want to make your bot more complicated, you just have to modify the decision-making behind the tweets.

The entirety of the code in this example can be found on github here. An intro to python can be found here.

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