ruby snippets

gistfile1.rb

*`which` in ruby* 
http://stackoverflow.com/questions/2108727/which-in-ruby-checking-if-program-exists-in-path-from-ruby
def which(cmd)
  exts = ENV['PATHEXT'] ? ENV['PATHEXT'].split(';') : ['']
  ENV['PATH'].split(File::PATH_SEPARATOR).each do |path|
    exts.each { |ext|
      exe = "#{path}/#{cmd}#{ext}"
      return exe if File.executable? exe
    }
  end
  return nil
end

*sort descending hash based on value*
a = {"earn"=>2, "acq"=>11, "trade"=>3}
1) a.sort_by{|k,v| -v}
2) Hash[*a.sort{|a,b| b[1]<=>a[1]}.flatten]

*check if a string is number*
http://stackoverflow.com/questions/5661466/test-if-string-is-a-number-in-ruby-on-rails
class String
  def is_number?
    true if Float(self) rescue false
  end
end