# File lib/visage-app/collectd/json.rb, line 108
      def percentile_of_array(samples, percentage)
        if samples
          samples.sort[ (samples.length.to_f * ( percentage.to_f / 100.to_f ) ).to_i - 1 ]
        else
          raise "I can't work out percentiles on a nil sample set"
        end
      end