Ruby/Rails: Can't get Bantik's heatmap code to work

I'm playing with the code available here (GitHub repository here) to generate a heatmap/cloud.

I'm running into a lot of NoMethodErrors and other problems that prevent the page from even being rendered. The two or three times the page did render, the cloud didn't display properly. I would appreciate any and all help in getting this working so I can play with the code.

The error of the hour is:

undefined method `each_pair' for "Many":String

This is referencing my view:

<h1>Title</h1>
.
.
.
<% stylesheet_link_tag "custom" %>
<%= heatmap( {"Foo" => 13,
  "Bar" => 15,
  "Trouble" => 5,
  "Braids" => 1,
  "Something" => 9,
  "Else" => 13,
  "Many" => 20,           <----
  "Zombies" => 7,
  "nothing" => 0}) %>

I'm dumping the test hash directly into the view because I was getting a:

undefined method `keys' for nil:NilClass

For completeness, this is my ApplicationHelper (where the heatmap method is defined):

module ApplicationHelper
  def heatmap(histogram={})

  content_tag(:div, :class => "heatmap")

    histogram.keys.sort{|a,b| histogram[a] <=> histogram[b]}.reverse.each do |k|
      next if histogram[k] < 1
      _max = histogram_max(histogram) * 2
      _size = element_size(histogram, k)
      _heat = element_heat(histogram[k], _max)

       content_tag(:span, content_tag( :class => "heatmap_element", :style => "color: ##{_heat}#{_heat}#{_heat}; font-size: #{_size}px;"), "#{k}")
    end

    content_tag(:br, :style => "clear: both;")
  end

  def histogram_max(histogram)
    histogram.map{|k,v| histogram[k]}.max
  end

  def element_size(histogram, key)
    (((histogram[key] / histogram.map{|k,v| histogram[k]}.sum.to_f) * 100) + 5).to_i
  end

  def element_heat(val, max)
    sprintf("%02x" % (200 - ((200.0 / max) * val)))
  end
end

I pulled the code out of the repository and used that in the helper instead. I have changed the code to use content_tags because the app was开发者_如何学JAVA escaping the HTML code and printing it on the site.

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Heres how I implemented it...https://gist.github.com/3505320. Good luck!