Todd Gardner wrote:

> My goal is to have my application plot arrays of (x,y) and possibly
> (x,y,z) data points in "real time".  I would also like to write text
> on the graphs.  I would like to ask for a knowledgeable comparison and
> contrast of the multitudes of graphic utility libraries out there
> capable of doing this seemingly SIMPLE plotting.

....

> WxRuby - I don't know how to draw lines yet in this library.

In WxRuby you could use a Device Context to draw lines, points, fills, 
ellipses, etc, plus text onto a frame. For a full list of methods 
available see the WxWidgets docs:

http://www.wxwidgets.org/manuals/2.4.2/wx105.htm#wxdc

I haven't used these classes in detail, so I don't know whether the 
bindings are complete, but the following simple example worked for me 
using wxruby-0.3.0 (current release is 0.4.0)

chrz
alex

---------------------------

require 'wxruby'

class MyDrawingFrame < Wx::Frame
   def initialize(*args)
     super(*args)
     evt_paint { on_paint }
   end
   def on_paint
     paint do | dc |
       dc.clear
       dc.draw_line( 0, 0, 50, 100)
       dc.draw_line( 50, 100, 100, 75)
       dc.draw_text( 'a label', 52, 102)
     end
   end
end

class MyApp < Wx::App
   def on_init()
     frame = MyDrawingFrame.new(nil, -1, 'Drawing')
     frame.set_client_size( Wx::Size.new(200,200))
     frame.show()
   end
end

MyApp.new().main_loop()