Eve-trader.net – the new source for EVE Online productioneers

Greetings, capsuleers!

Few days ago I launched my long time dreamed project – eve-trader.net (http://eve-trader.net). This services is intended to be a lightweight alternative to updating your excel sheets daily with current prices (most likely you will get them from eve-central.com). Via the eve-central.com API I fetch the prices on requested blueprints, calculate for you the cheapest material prices and suggest where you can sell the end product most expensive.

Settings and assumptions as of today:

  • Areas considered for calculation are all solar systems within 5 jumps around the five main trade hubs (which currently are – Jita, Amarr, Rens, Dodixie, Hek) and which are high sec
  • All skills are lvl 5 (which you probably should have if you considering make money with industry)
  • No fees and taxes are calculated (if they are hindering you to make profit you are producing the wrong thing)

The service is in it’s early stage, so be prepared to encounter some changes in near future. What is planned:

  • Having at least a few options available in an “expert” menu
  • News section
  • Implement user accounts where user can save their blueprints, thus, having a faster access to their favourite blueprints
  • Having a history saved for each blueprint.
  • A suggestions feature, where users can suggest new things and other users can vote on them.
  • Making market predictions based on Monte-Carlo-Simulation or Expected Shortfall methods.

All hail Gaben… ehm optimization!


After optimization:

Hashtag “inlovewithruby” 🙂

From 14.727 seconds to 0.012306 seconds, that’s 1196 times increase.

Rails eShop – my first big project using Ruby on Rails

[readolog_dropcap ]H[/readolog_dropcap]appy new Rails year, fellow riders!


I finished my very first “serious” project – yay! It looks and behaves like a rails eShop (you can find link further down below). Before I go into technical details some intro – this website was created for friends of mine and although it was kind of experimental for me (first real app), it turned out to be quite decent as one might say so.

As with every customer-oriented project, there was a lot of JavaScript involved, which is by far not my strongest language. It started calm and nicely with pure ruby on rails, I could use a lot of stuff I learned from this book – Agile Web Development With Rails. But then… as more and more wished appeared I realized that there is no way around some front-end development.

Enough smalltalk, let’s get straight to the data:

  • Bootstrap Theme used – “Minimal
  • Notable gems: figaro (managing global variables), devise (users), carrierwave (images uploads), sendgrid (for sending any kinds of mails)
  • Database: postgresql (I think it’s pretty a must-have for shops because of hstore – which, as far as I understand makes postgres almost non-relational, because hstore columns allow to store hash/value pairs)
  • Deployment: capistrano, puma, nginx (you can check out my article about deployment here)
  • Other features: protected admin namespace

[readolog_dropcap ]M[/readolog_dropcap]ost notable code


JavaScript – a calculator for end value of a product based on amount, delivery method and size (plus additional services, which are to be differentiated between one for each product and one for a full order). There is some hard coded stuff and of course this piece of code might not be the state of the art, however it works pretty well.

Here we have some fancy helper methods which I grabbed from Ryan Bates screencasts. They allow you to add fields on the go:

[readolog_dropcap ]L[/readolog_dropcap]ast, but not least


we have of course a fully functional rails eShop with a working cart, order placement, sending confirmation letters to customers and admins, an administration panel for managing products etc. etc.

Unfortunately the owners decided to put this page on ice, therefore it’s unlikely that you will receive some flash drives. However you can check the page out all by yourself – http://souvenirnya-produktsiya.ru/


Beautiful strings

Today I found an interesting challenge on CodeEval – it’s from Facebook Hacker Cup 2013 Hackathon. At first I had my issues with understanding the task. Here’s the description:

[readolog_blockquote ]Given a string s, little Johnny defined the beauty of the string as the sum of the beauty of the letters in it. The beauty of each letter is an integer between 1 and 26, inclusive, and no two letters have the same beauty. Johnny doesn’t care about whether letters are uppercase or lowercase, so that doesn’t affect the beauty of a letter. (Uppercase ‘F’ is exactly as beautiful as lowercase ‘f’, for example.)

You’re a student writing a report on the youth of this famous hacker. You found the string that Johnny considered most beautiful. What is the maximum possible beauty of this string?[/readolog_blockquote]

Your input are few lines of senseless strings. Output should be a number, a sum of values for every letter. In other words this challenge can be described as following:

[readolog_blockquote ]Count encounters of every letter. Since you can use every number only once and your goal is to produce the biggest possible sum you should assign the bigger numbers to letters, which occur most often.[/readolog_blockquote]

If there are letters with same presence amount it makes no difference to which you assign the exact number. Let’s say you have three ‘a’, three ‘b’ and three ‘c’. If you decrease your assignment by one each time it won’t matter to which exact letter you’ll assign exact number, since the math is 3*26 + 3*25 + 3*24 and it doesn’t care to which letter ‘belongs’ the number ‘3’.

So here is my code. I’m sure it can be done in a one-liner, however I wouldn’t consider this challenge as trivial, therefore I’m a bit proud of my solution.