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• How many people are around me?

  In my city there is one library where I like to study. But during exam times it’s overcrowded and the good study places are gone fast. So I wondered: When are there how many people? How could that be easier in those days where everyone not only has a smartphone but most have tablets and laptops too.

• A bot working for me

  When I talk about bots with people, they usually see some machine replacing people (and destroying something). They miss that a bot is nothing more than a sophisticated algorithm. It seems hard to understand that a manual (= simple algorithm) can be automated (= script) and one can let it work the whole day.

• A drone following my hand

  Some time ago I bought a parrot AR drone 2.0 and thought I would be nice to make it more autonomous. The idea came from this guys who made a drone following a trail (paper, youtube) and from having a dog. Since the drone doesn’t have much sensors, I’d have to do the most out of it’s front camera.

• Build a 3x3 LED matrix and spot the ISS

  When I was young I used to have a telescope. With that and viewing tables I used to look at planets and stars. Somehow I missed to ever look at a satellite or the ISS. I wanted to catch up for that.

• Loops with recursion

  This post is about theoretical stuff. When I was young (15y), my first attempt to program something bigger was a compiler. It should compile my own language into C++ and was itself written in C++. I was fascinated by the possibility to design an own language. However, I was determined to fail. Basically because I lacked some knowledge in C++. I still got pretty far: I developed an abstract syntax tree (AST) and wrote a working parser (my language -> AST), but failed to build a working interpreter (AST -> C++). The language I developed was simple: It had no

• Meteor.Js publish and subscribe

  TLDR: Read the f*** manual. I didn’t read the meteor docs carefully enough: Not all published rows are sent to the client, only the needed ones. See here for further explanations.
  This answers my questions from this post.

• Why style matters

  I hypothesise that one needs style to succeed. Obviously one needs skill and hard work, but why style?

• Paul Graham's Essays

  I read most of Paul Graham’s Essays.

• Web scraping with Node.js

  The last days I was building a web scraper-app, who get and stores data from sites and from where I can download the data in CSV. I used node.js, express, mongoDB and other packages. Things that surprised me:

• Spam-filter for websites

  Since I felt a bit ill tonight, I stayed at home and fiddled around with naive Bayes classifiers for spam filters (wiki). I had the idea that it should be possible to build a greasemonkey/tampermonkey script which removes (or greys out) all the unwanted and attention seeking stuff in the internet besides ads. Things like “related”-stuff, “you also like”, news which are not really news and all that unrelated content, maybe it could be expanded to trolls in forums. I thought about a filter based on the text and html-classes which classifies the content as spam or not.

• Automated trading

  Three years ago I built an automated trader for bitcoin (BTC/USD), which I uploaded to a free hosting and let it work (it was build in Python because I wanted to learn Python). First I did test runs only, simulating a portfolio (the order book was visible, so I could estimate if a trader would’ve been made). I used very simple algorithms like weighted moving average, bollinger bands and donchian channel, tried around a bit with the lengths/parameters and that did it. After some time I went live and made a bit of money: about 10-20 CHF / day (1 CHF

• Cron for Node.js on Openshift

  If you want to install a cron job for Node.js on Openshift. I’m assuming that Node.js is already installed.