barinek.com: the official website

calculating median values via mysql

Here is a quick mysql sql snippet that I used to calculate median values grouped by year…

select a.year, avg(a.rownum), avg(a.value) from (
select if(@current_year=year, @rownum:=@rownum+1, @rownum:=1) as rownum, 
@current_year:=year as year, amount as value from (your_data_or_select) as amounts, (select 
@rownum:=0) as r, (select @current_year:=0) as y order by year, amount) as a,
(select year, 0.5+count(*)/2 as median from (your_data_or_select) as amounts group 
by year) as b
where a.rownum between (b.median - 0.5) and (b.median +0.5) and a.year = b.year 
group by a.year;

results = ActiveRecord::Base.connection.execute(sql)

Rails 3 with RVM and Cruise Control

Here are a few notes on how to get individual CruiseControl.rb project Builders running with RVM. [Note: I’m making an assumption here that you know and understand Bundler and RVM.] [Also: Cruise may or may not be running on RVM] Create and check in a .rvmrc file in your rails root directory. Here’s an example.

rvm ruby-1.8.7-p174@rails-example

Project.configure do |project|
  project.build_command = './cruise_build.sh'
end

#!/bin/sh

source $HOME/.rvm/scripts/rvm && source .rvmrc

rake cc:build

(Source: pivotallabs.com)