Enhancing special data source with graph-related values

[mortomanos]

Hello all,

is there a way to get something like the calculated lower boundary of the graph (not the lower limit!) and the unit size of the y-axis?

What I want to achieve is the following: a graph that shows the air temperature (this can be negative of course) should include an indicator if it is raining or not. This value is available not in ml/mm² or anything similar, only a binary value (raining or not raining). So I want to have a line graph that is "0" or "1" with "0" mapped on the calculated lower boundary of the graph, and "1" mapped to 0.4 times the unit size.

If someone could help me, this would be great.

[gandalf]

I'd try to graph this as a color, not a numeric value.
Find some examples in the documentation in the CDEF section or on the www.
So you may use a light blue background when it's raining, otherwise white or whatever you fancy
R.