controller

def index
  @plans = Plan.all
  @graph = Graph.new(@plans)
end

graphs

class Graph
  GRAPHS = {
    roi: ReturnInvestment,
    extra_pay: ExtraPay,
    profit: Profit
  }
  private_constant :GRAPHS
  
  def initialize(plans)
    @plans = plans
  end
  
  def data_for(graph_identifier = :roi)
    GRAPHS[graph_identifier].new.data(@plans)
  end
end

class ReturnInvestiment
  def data(plans)
    plans.each_with_object({}) do |plan, graph_data|
      graph_data[plan.name] = plan.return_of_investiment.round(2)
    end
  end
end

class ExtraPay
  def data(plans)
   plans.each_with_object({}) do |plan, graph_data|
      graph_data[plan.name] = plan.extra_pay_total.round(2)
    end
  end
end

class Profit
  def data(plans)
    plans.each_with_object({}) do |plan, graph_data|
      graph_data[plan.name] = plan.profit.round(2)
    end
  end
end

view.erb

<%= javascript_include_tag "http://www.google.com/jsapi", "chartkick" %>
<div class="container">
  <div class="row">
    <div class="col-md-offset-2 col-md-8">
      <div class="page-header">
        <h3>Financials</h3>
      </div>
      <% if @plans.empty? %>
      <div>
        No plans available.
      </div>
      <% else %>

        <%= pie_chart @graph.data_for(:profit) %>
        <p class="chart-label">Profit by plan chart<p>

        <%= column_chart @graph.data_for(:roi) %>
        <p class="chart-label">Return of investiment chart<p>

        <%= column_chart @graph.data_for(:extra_pay) %>
        <p class="chart-label">Extra pay by plan chart<p>

      <% end %>
    </div>
  </div>
</div>