Line graph with error band

Example of line graph with error band.

The function draws a series of quadrilaterals whose vertices matched pairs of the two series data_up and data_down then inserting a line is the average values.
To actually use series with variable error just simply change the code by passing the three sets as parameters instead generate randomly.

test_it_controller.rb

class TestItController < ApplicationController
def index
 @graph1 = open_flash_chart_object(600,300,"/test_it/graph1_code")
end

def graph1_code

 title = Title.new("a Graph")

 chart = OpenFlashChart.new
 chart.set_title(title)

 @data_up = [1]
 @data_down = [-1]

 0.step(30, 1) {|i|
     @data_up << @data_up[i] +rand - 0.5
     @data_down << @data_down[i] + rand - 0.5
     }

 def draw_quadri(i)
   q = Shape.new( '#80B11A' )                        
   q.append_value(ShapePoint.new(i,@data_up[i]))
   q.append_value(ShapePoint.new(i,@data_down[i]))
   q.append_value(ShapePoint.new(i+1,@data_down[i+1]))
   q.append_value(ShapePoint.new(i+1,@data_up[i+1])) 
   return q
 end

 flux = []
 (@data_up.length-1).times do |h|
   flux << draw_quadri(h)
   end

 flux.each do  |shape|
    chart.add_element(shape)
    end

 scatter_line = ScatterLine.new( '#FF0000', 5 )
 scatter_line_u = ScatterLine.new( '#FF0000', 3 )
 scatter_line_d = ScatterLine.new( '#FF0000', 3 )
 data = []
 data_u = []
 data_d = []

 x=0
 (@data_up.length).times do |h|
   data   << (ScatterValue.new(x,(@data_up[h] + @data_down[h])/ 2))
   data_u << (ScatterValue.new(x,@data_up[h]))
   data_d << (ScatterValue.new(x,@data_down[h]))
   x+=1
   end

 scatter_line.set_values(data);         chart.add_element(scatter_line)
 scatter_line_u.set_values(data_u);     chart.add_element(scatter_line_u)
 scatter_line_d.set_values(data_d);     chart.add_element(scatter_line_d)

 x = XAxis.new
 x.set_range(0,32,5)
 x.set_offset(false)
 chart.set_x_axis(x)

 y = YAxis.new
 y.set_range(-5,5,1)
 y.set_offset(true)
 chart.set_y_axis(y)

 render :text => chart.to_s
end
end