Project Ideas

Doing is the best way to learn, and since learning is what we're here for, let's do some stuff. I've had a number of different ideas for projects recently and not so recently, so to offer you some inspirations and perhaps for me to see if any of these still make sense when you see them typed out, I've compiled a little list of them. (Some of these are actually projects I've already started working on)

• "Multiplayer" Paint. Basically, this would be like a chat program that lets two (or more?) people draw on the same canvas as one would in mspaint. I would implement this in C++, just because I want to learn more about it (and graphics / network programming) but also because most people don't have Python interpreters with pygame on their machine. It might be time for something different :)
• Javascript multiplayer Paint! Use a JS canvas for client side, and save the changes to canvas stored server side (maybe use php, or node.js for serverside scripting?) Then, everyone who visits the page can draw on it for everyone else to see. Obvious downsides of this however are the fact that this is still the internet, and I suspect sooner or later (sooner) it will meet a similar fate tot that of Chatroulette
  
• A 3-4 DoF Robotic arm. It doesn't have to be a very good one either, just to keep costs down. Forward and inverse kinematics are pretty interesting, and this would be a good way to learn and practice both. Servos can be picked up pretty cheaply as well, and the whole thing could be run from an Arduino - the only real difficulty in this would be the mechanical parts, I have no good way of making them properly. I got this idea from...
  
• .. building a hexapod. 3DoF would be minimum for each leg to be able tog et decently smooth motion, the problem is that this would be a rather costly product (for me, at least)
• A simple webcrawler. I don't know what you would use it for, but my ideas were perhaps a Reddit bot (find/keep track of reposts, produce statistics based on comments, find most used pun of the day, etc.), or a Wikipedia crawler (create a graph of pagelinks, those are always neat)
• On a similar note, implementing a graphing layout algorithm - finding a good layout for graphs (graph meaning a set of nodes connected by edges) automatically. There are different ways to implement this, the spring model seems like the simplest: each edge is like a spring that pulls two connected nodes together, or pushes them apart based on their distance from each other. One could also base the pushing/pulling force on the "weight" of each node (weight could be number of incoming edges, for example)
• implement quantitative stock trading algorithms. This is something I personally find really interesting, though I haven't worked on it much. Wikipedia has a nice page about the different algorithms that are used today. A technical problem that needs to be solved first is getting a decent sample of historical data for a given stock, as this is very often necessary for such algorithms.

Of course these all aren't new ideas, but I've found that I usually have good ideas while working on something else, and these are just inspirations for you anyway. Potentially all of these are good for learning something new!

MaterialMaker tool for TUM informatics

I've been meaning to try out some C# programming, so I collaborated with a friend of mine who is pretty experienced with it on a small but useful project - a tool to automatically download and display our class materials. He had already coded up the interface and execution logic during a particularly boring lecture, but it was all hardcoded to his filesystem and required the materials to already be downloaded and in the right folders. I figured it would be useful to add some functionality and let the program automatically download the latest materials and organize these in a generic directory it creates itself.

To get to the materials, I used RSS links that contained .pdfs and .zips of all the files. I wrote some parsing logic for these, which basically looks for tags and then extracts the direct link to the file. The filename is then checked with the local folders, and if it isn't already there, the file is downloaded.
Screenshot:


If you're a CS student at TUM and would like to use this tool, you can download it from my website: http://home.in.tum.de/~dowling/index.html. It shouldn't be too hard for me to add support for other classes, if you're interested just shoot me a message.

Progress on pyGates

Yesterday I wrote a short paragraph about a project I recently started, a logic gate simulator written in Python (short: pyGates). I spent a night and most of todays classes coding on it, and it's starting to get to a point where it's almost usable. I still need to implement a few more things such as switches and lightbulbs, perhaps I'll add some higher-level logic chips later on, but the basic structure is put together and the wires will also finally behave properly (in terms of connecting to the right sockets and staying there, that is).

Next up is fixing up the graphics, the main thing here is to put in the standardized symbols for the different gates, and making the wires look nice (I'll probably have them hang down as though they were loose cables, similar to logicly). Below is a screenshot of what the program currently looks like (yes, the gates look the same even though they serve different functions).

Basic stock price functions in Python

I've been reading a bit into algorithmic stock trading lately, and thought I'd try and actually simulate a few of the trades strategies. The first thing I needed was a way to get at the stock prices, I figured the easiest way might be scraping either Yahoo or Google Finance. Turns out someone else has done this before, so no need to code it up myself. I think Google Finance has been updated since that module was written, because the regex used doesn't properly fetch the actual price. All I had to do was modify the function in a few places and everything was working as expected.
A neat thing about it is that you don't need to pass the exact ticker symbol you want to get a quote for into the get_quote function, since the stirng gets passed as a query to Google Finance, which autocorrects it.

I also added a stock class, as well as long and shot sell functions. This should be a good enough start to simulate some algorithmic trading.

pyGates

Something I've recently thought about was creating a small logic gate simulator which lets you build simple digital circuits. I've seen this elsewhere before (http://logic.ly/), with a very neat implementation but unfortunately that software now costs money. It shouldn't be too hard to brew something like this together, so I'll give this a shot over the next couple of days and see how it goes. I'll be using python for now just because I like working with it the most, but I might take this as an opportunity to learn JavaScript and host this online. I've already started working on this and have the basic structure together, all it is really is a pygame canvas with gate-objects and a few other things, but it may still take some time until it all comes together in a usable way. I'll keep you posted.

Complete ROAMR setup

This is my robot in it's complete setup, of course I'll work on actually fixing everything in place properly, but all the hardware and such is there. I haven't been able to reliably send the Kinect data over wifi using ROS, so unfortunately the mapping and navigation algorithm isn't implemented yet, however I am controlling the robot from my laptop remotely over ROS. There are nodes running on each of the computers:

• The controlling laptop publishes steering data (this is what you see running in the terminal at the beginning)
• The robot in turn listens to this steering topic, and writes the appropriate signal to the Arduino onboard, which then controls the actual motors.
• The robot also publishes the Kinect data over ROS topics, however they don't seem to get through (my network stats show that the outgoing data constantly peaks at around 230KiB/s, but no actual images get displayed on the host computer) I believe this is because of the poor wifi card built into the laptop on to of the robot, I'm currently working on getting this to work
• The controlling laptop listens in to this data, and will, once it's working, run it through the ROS RGB-D SLAM algorithm.

Eventually, I will try to implement odometry for the robot so I can use the ROS gmapping algorithm instead, which produces 2D maps of the robots environment and better allows for navigation. i also expect the resulting maps will be much smaller in filesize - the RGB-D SLAM produced maps are often several GB large.

Here's the video:

Another post in the Quining series

The other day I revisited some of the scripts I wrote when messing with self-replication /-modification, and noticed that it wouldn't be hard to automate the process of turning a program into a quining one. So I decided to write a little script that does exactly that - you simply give the filename of the python script you want quined, and it will produce a new script with the source code of the old one, plus additional code that will make that script return its own source code in a new file when exectuted. Hopefully this isn't too confusing, but it was certainly at times confusing to write, even though it's a fairly short script.



The real fun starts when you execute this script on itself.. you get a quining quine. Now repeat ad-infinitum.