search for: stripplot3

...http://i46.tinypic.com/2h7gpvn.png But this is not enough. I want to measure the distance between 2 successive knots (the difference between 2 successive dates) and note on the plot the number of weeks that separate apart the successive knots-dates Something like http://www.survey-design.com.au/stripplot3.png where as you can see between the knots there are some red lines. In my case these red lines would inform the reader about the number of weeks between successive knots-dates I need a specific code for this because a simple hint will not help me as I am a new R user. Thank you all