Rendering google style pie chart in your rails app

5 Mar 2009, by Michael Cindrić

Google has some of the best charts on the web. If you ever wanted to have cool pie charts like google here is a simple way to do it. Simply add the following to your application_helper.rb file.

  def google_pie_chart(data, options = {})
    options[:width] ||= 250
    options[:height] ||= 100
    options[:colors] = %w(0DB2AC F5DD7E FC8D4D FC694D FABA32 704948 968144 C08FBC ADD97E)
    dt = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-."
    options[:divisor] ||= 1

    while (data.map { |k,v| v }.max / options[:divisor] >= 4096) do
      options[:divisor] *= 10
    end

    opts = {
      :cht => "p",
      :chd => "e:#{data.map{|k,v|v=v/options[:divisor];dt[v/64..v/64]+dt[v%64..v%64]}}",
      :chl => "#{data.map { |k,v| CGI::escape(k + " (#{v})")}.join('|')}",
      :chs => "#{options[:width]}x#{options[:height]}",
      :chco => options[:colors].slice(0, data.length).join(',')
    }

    image_tag("http://chart.apis.google.com/chart?#{opts.map{|k,v|"#{k}=#{v}"}.join('&amp;')}")
  rescue
  end

Once you have that in then in your view its as simple as below to render a nice pie chart. Go ahead have a piece.


 <%=  google_pie_chart([["Rails",80],[".Net",10],["Java",10]) %>