Valentin Mihov's Blog

Random pieces of wisdom about technology

Adult Income Data Set Analysis with IPython

In this blog post I will show you how to slice-n-dice the data set from Adult Data Set MLR which contains income data for about 32000 people. We will look at the data and build a machine learning model (a logistic regression), which tries to predict if a person will make more than $50K a year, given data like education, gender and martial status.

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Rails + EmberJS + Active Model Serializers + Her

Recently I got into a situation at work, where there was a Rails app, which was exposing some data through an API which uses active_record_serializers and EmberJS as front-end of the data. The problem was there needed to be a new Rails app, which also consumes data from the same Rails API endpoints and visualize the data. Unfortunatelly ActiveResource and Her are not supporting the ember-data kind of data format, which requires to have separate serializers for EmberJS and for regular Rails API calls. So the ember_data_active_model_parser was born, which is a middleware for Her, which makes it understand the ember-data JSON format.

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Home automation: research and choosing hardware

I decided to make a self made home automation system in my apartment. The reason is that I figured out that turning on and off my heating when I am not around reduces my electricity bill by 50%. My current schedule is to turn off the heating when I leave the house and turn it on 1 hour before I come back home. I do the same thing with the heating in my bedroom. The heating there is turned on about an hour before I go to sleep and I turn it off during the day. However there are exceptions from these rules especailly around holidays, so an automation system should also be very configurable.

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Running Ruby 1.9.1 + Rails + MySQL and unicode characters

If you have tried to develop some rails application on Rails + Ruby 1.9.1 and MySQL database and you are storing non-English characters in your database probably you had a lot of pain with errors about incompatible charsets. This is a known problem and there is even a bug in Rails’ lighthouse for it. There is even a hack which is going around the issue. The solution is not perfect, but it works in most of the cases.

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My experience with developing a Rails 2.3.5 project with Ruby 1.9.1 Part 2

My journey into the ruby 1.9 land continues with some nice observations, tricks and tips.

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Switching my blog to jekyll and compass

Probably you remember that some time ago I decided to switch my blog from blogger to a custom made blogging engine written my me. It was a simple sinatra app, which was parsing a bunch of markdown files, which were the posts and rendering the blog.

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My experience with developing a Rails 2.3.5 project with Ruby 1.9.1 Part 1

I decided to use ruby 1.9.1 for my next project. One of the reasons I decided so is because ruby 1.9 is definitely faster than 1.8 and also it has a superior encoding support for the strings. Not to mention that living on the edge is a thrill :-)

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Integrating custom SQL queries with ActiveRecord

I know that some people could start a flame war about what I will discussing right now, so let me first introduce you into the context of the problem.

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A task for admission of gifted children in Japan

This is a task that was given to a group of children for admission in kindergarten for gifted children in Nagoya, Japan. 74% of the children solved it. A hint: they were able to count up to 10.

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Ruby 1.9 vs. Ruby 1.8 real-life speed benchmark, no database

I am writing my blog with sinatra and I can proudly say that it runs with ruby 1.9.1 just fine. Unfortunately the hosting on heroku does not allow using ruby 1.9, so it runs 1.8 in production.

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