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.

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.

Results

HPC 4 Life

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.

Setup

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

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.





Heaping scoop, fine-ish grind.

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.

Account Setup

Astrophotography Manual Barn Door Tracker

Motivation

After seeing some beautiful photos of the milky way, I wanted to step up my astrophotography game a little bit. In astrophotography, you are limited to shutter speed = 500 / (focal length) before your stars get blurry from the earth's rotation. To get better photos of the night sky, you can use what is called a tracker which allows you to take much longer exposures.

They are also quite expensive, and not particularly complicated. So I decided to try making one myself. The goal was to make it simple, and cheap. In the end, the total was less than $50, and the results have been quite successful.

It was so simple to build in fact, you probably don't even need a guide once you understand the key concepts. So I'll start with the basics of how and why it works, followed by a breakdown of how I built it.

Here is the final product:

and some results:

2.5 minute Milky Way exposure

Vice City: Python Automated Sports Betting

Automated Sports Betting

Everyone knows gambling is a great way to make money (/s). I myself formed this conclusion after hearing bookies will sometimes pay out before an event even happens, which planted a betting strategy in my mind that required a bot. This very successfully and slowly lost me my $50 investment, but I had a lot of fun making it, so I thought I would share the project.

If you use this guide, please don't be stupid. Basically nobody comes out on top in the sports betting world. It's not going to be you! So maybe have some fun testing out theories, or let a robot lose money on your favourite sports team, but be prepared to lose any money you deposit in your Pinnacle account.

This is my first tutorial, so if you use this project I'd love to hear how it goes. If you manage to make a lot of money, a donation to Wikipedia would be appreciated.

Now let's get down to the coding. Taking a look at the official API documentation  at this point would be wise as well. All the source code referenced can be found at my github here, along with any future bug fixes. An intro to python can be found here.

In my bot, there are three essential stages.

1. Gather information. (Balance, Odds)
2. Check Criteria. (Find desirable bets)
3. Place bet.

Wanderers

One of the coolest mix of special effects and real images I've ever seen. Simply stunning.

Wanderers - a short film by Erik Wernquist from Erik Wernquist on Vimeo.