Exclude middle blank portion in TGraph

I was plotting zenith angle of a source vs rates, its minimum angle is 30 degree, and i am taking data upto 50 degree, when i plot using TGraph it include whole values from -50 degree to 50 degree(mean it shows blank on x-axis between -30 to 30 also), but i want to view data from
-50 degree to -30degree and 30 degree to 50 degree. and exclude middle blank portion in graph.

Either exclude the points you do not want to see from teh graph
or create 2 graphs, one for each side

Rene