[R] Broken x-axis?

[Brett Ginsburg]

Hello, 
Sorry for the double post, but I just subscribed....

Does anyone have experience creating a graph with a segmented x-axis?

Specifically, as a pharmacologist, I frequently need to create a graph with
2 segments, one for vehicle, and one for active doses.

Here is an example...

|
|
|
|
 |----|   |----------------|
 Vehicle    1  3  10  30  etc..
              Doses

Any help is appreciated!

Thanks,

Dr. Brett C. Ginsburg
Division of Alcohol and Drug Addiction
Department of Psychiatry
The University of Texas Health Science Center at San Antonio
7703 Floyd Curl Dr.
San Antonio, TX 78229

Phone: 210-567-0871
FAX:   210-567-5381