Hi all

I need to draw a graph with the following structure:

Each observation (data point) has 3 attributes : id, value, time. The good thing is that all these entries are positive.

I want to have a two dimensional graph showing all these 3 things. Since, all the entries are positive I can exploit that feature in the following way: I want the id on the x-axis and value on the positive y-axis and the time on the negative y-axis.

Any idea how to generate this graph ?

Thanks a lot.